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CARNEGIE INSTITUTION 
OF WASHINGTON 



YEAR BOOK No. 39 
July 1, 1939— June 30, 1940 

With Administrative Reports through December 13, 1940 




CARNEGIE INSTITUTION OF WASHINGTON 

WASHINGTON, D. C. 

1940 



LORD BALTIMORE PRESS 
BALTIMORE, MARYLAND 



CONTENTS 

PAGES 

Officers and Staff v— x 

Organization, Plan, and Scope xi 

Articles of Incorporation xii— xiv 

By-Laws of the Institution xv-xviii 

Abstract of Minutes of the Forty-second Meeting of the Board of Trustees xix-xx 

Report of the Executive Committee xxi— xxiii 

Report of Auditors xxiv— xxxi 

Report of the President i— 16 

Reports of Departmental Activities and Cooperative Studies 
Astronomy 

Mount Wilson Observatory 3- 26 

Special Projects: 

S. A. Mitchell 27-28 

Terrestrial Sciences 

Geophysical Laboratory 29— 54 

Department of Terrestrial Magnetism 55— 1 12 

Special Projects: 



Committee on Coordination of Cosmic-Ray Investigations Ix 3 — 

Robert B. Brode 

A. H. Compton 1 16- 

S. E. Forbush 121- 

V. F. Hess 124- 

Thomas H. Johnson 125- 

S. A. Korff 127- 

Robert A. Millikan 130- 

M. S. Vallarta 

Committee on Study of the Surface Features of the Moon I 3 2- 

California Institute of Technology I 34~ 

V. Bjerknes 

Edward L. Bowles J 3^- 

Joseph C. Boyce J 37 - 

F. A. Perret 138- 

Biological Sciences 

Division of Plant Biology 141- 

Department of Embryology J 79 _ 

Department of Genetics 201—231 

Nutrition Laboratory 233-238 

Special Projects: 

Katherine S. Brehme 239 

Philip N. Bridges 239-240 



CONTENTS 

PAGES 

Barbara S. Burks 240-242 

Paul S. Conger 242-244 

Th. Dobzhansky 244—247 

Charles Elton 247—248 

Robert G. Green 249—250 

Arthur T. Hertig 250 

T. H. Morgan, Jack Schultz, and Viola Curry 251—255 

E. G. Ritzman 256-257 

H. C. Sherman 257-259 

Historical Research 

Division of Historical Research 261—285 

Special Projects: 

Marion E. Blake 287 

Frans Blom 287 

Verne E. Chatelain 288-289 

E. A. Lowe 289 

Paleontology, Early Man, and Historical Geology: John C. Merriam and 

Associates 290-312 

Chester Stock 291—292 

Eustace L. Furlong 292—293 

John P. Buwalda 293-294 

Remington Kellogg 294—295 

E. L. Packard 295-296 

Ralph W. Chaney 296-297 

Edwin D. McKee 297-299 

Ira S. Allison 299-300 

L. S. Cressman 300—306 

Ernst Antevs 306-309 

E. B. Howard 309-312 

Publications in Connection with Other Projects 312 

Bibliography 3 1 3—3 1 5 

Index 317-326 



PRESIDENT AND TRUSTEES 



Thomas Barbour 
James F. Bell 
Robert Woods Bliss 
Lindsay Bradford 
Frederic A. Delano 
Homer L. Ferguson 
W. Cameron Forbes 
Walter S. Gifford 



Robert Woods Bliss 
Vannevar Bush 



PRESIDENT 
Vannevar Bush 

BOARD OF TRUSTEES 

W. Cameron Forbes, Chairman 

Walter S. Gifford, Vice-Chairman 

Frederic A. Delano, Secretary 

Herbert Hoover 
Walter A. Jessup 
Frank B. Jewett 
Alfred L. Loomis 
Roswell Miller 
Henry S. Morgan 
Seeley G. Mudd 
Stewart Paton 

Executive Committee 
W. Cameron Forbes, Chairman 
Frederic A. Delano 
Walter S. Gifford 
Walter A. Jessup 



John J. Pershing 
Elihu Root, Jr. 
Henry R. Shepley 
Richard P. Strong 
Charles P. Taft 
James W. Wadsworth 
Frederic C. Walcott 
Lewis H. Weed 



Frederic C. Walcott 
Lewis H. Weed 



Finance Committee 
Frederic C. Walcott, Chairman 
Lindsay Bradford Henry S. Morgan 

Walter S. Gifford Elihu Root, Jr. 

Auditing Committee 
Frederic A. Delano, Chairman 



Robert Woods Bliss 



James W. Wadsworth 



STANDING COMMITTEES FOR THE YEAR 1941 
Committee on Astronomy 
Herbert Hoover, Chairman 
Walter S. Gifford Seeley G. Mudd 

Roswell Miller Elihu Root, Jr. 

Committee on Terrestrial Sciences 
Frank B. Jewett, Chairman 
Frederic A. Delano Henry S. Morgan 

Homer L. Ferguson Frederic C. Walcott 



Committee on Biological Sciences 
Lewis H. Weed, Chairman 



Thomas Barbour 
James F. Bell 



Alfred L. Loomis 
Stewart Paton 



Committee on Historical Research 
Henry R. Shepley, Chairman 
Robert Woods Bliss Charles P. Taft 

Richard P. Strong James W. Wadsworth 

v 



FORMER PRESIDENTS AND TRUSTEES 



PRESIDENTS 

Daniel Coit Gilman, 1902-04 Robert Simpson Woodward 

John Campbell Merriam, President 1921—38; President Emeritus 1939 — 



, 1904-20 



TRUSTEES 



Alexander Agassiz 
George J. Baldwin 
John S. Billings 
Robert S. Brookings 
John L. Cadwalader 
William W. Campbell 
John J. Carty 
Whitefoord R. Cole 
Cleveland H. Dodge 
William E. Dodge 
Charles P. Fenner 
Simon Flexner 
William N. Frew 
Lyman J. Gage 
Cass Gilbert 
Frederick H. Gillett 
Daniel C. Gilman 
John Hay 
Myron T. Herrick 
Abram S. Hewitt 
Henry L. Higginson 
Ethan A. Hitchcock 
Henry Hitchcock 
William Wirt Howe 
Charles L. Hutchinson 
Samuel P. Langley 
Charles A. Lindbergh 
William Lindsay 
Henry Cabot Lodge 



1904-05 


Seth Low 


1902-16 


1925-27 


Wayne MacVeagh 


1902-07 


1902-13 


Andrew J. Mellon 


x 9 2 4"37 


1910-29 


Darius O. Mills 


1902-09 


1903-14 


S. Weir Mitchell 


1902—14 


1929-38 


Andrew J. Montague 


1907-35 


1916-32 


William W. Morrow 


1902—29 


!9 2 5-34 


William Church Osborn 


1 9 2 7-34 


1903-23 


James Parmelee 


I 9 1 ?-3 I 


1902-03 


Wm. Barclay Parsons 


1907-32 


1914-24 


George W. Pepper 


1914-19 


1910-14 


Henry S. Pritchett 


1906-36 


1902-15 


Elihu Root 


1902-37 


1902-12 


Julius Rosenwald 


1929-31 


1924-34 


Martin A. Ryerson 


1908-28 


x 9 2 4-35 


Theobald Smith 


1914-34 


1902—08 


John C. Spooner 


1902-07 


1902—05 


William Benson Storey 


1 9 2 4-39 


1915-29 


William H. Taft 


1906-15 


1902-03 


William S. Thayer 


1929-32 


1902-19 


Charles D. Walcott 


1902—27 


1902-09 


Henry P. Walcott 


1910-24 


1902-02 


William H. Welch 


1906-34 


1903-09 


Andrew D. White 


1902-03 


1902-04 


Edward D. White 


1902-03 


1904-06 


Henry White 


1913-27 


1934-39 


George W. Wickersham 


1909-36 


1902-09 


Robert S. Woodward 


1905-24 


1914-24 


Carroll D. Wright 


1902-08 



Besides the names enumerated above, the following were ex-officio members of the Board 
of Trustees under the original charter, from the date of organization until April 28, 1904: 
the President of the United States, the President of the Senate, the Speaker of the House 
of Representatives, the Secretary of the Smithsonian Institution, the President of the 
National Academy of Sciences. 



STAFF OF INVESTIGATORS FOR THE YEAR 1940 
ASTRONOMY 



Mount Wilson Observatory 
Organized in 1904; George E. Hale, Director 1904— 1923, Honorary Director 1923— 1936 



Walter S. Adams, Director 
* Frederick H. Seares, Assistant Director 
Alfred H. Joy, Secretary 
Arthur S. King, Supt. Physical Laboratory 
John A. Anderson 
Walter Baade 
Harold D. Babcock 
William H. Christie 
Theodore Dunham, Jr. 
Joseph Hickox 
Edison Hoge 
Edwin Hubble 



Milton L. Humason 
Robert B. King 
Paul W. Merrill 
Rudolph Minkowski 
Seth B. Nicholson 
Edison Pettit 
Robert S. Richardson 
Roscoe F. Sanford 
Gustaf Stromberg 
Adriaan van Maanen 
Olin C. Wilson 
Ralph E. Wilson 



TERRESTRIAL SCIENCES 



Geophysical Laboratory 
Organized in 1906, opened in 1907; Arthur L. Day, Director 1907-1936 



L. H. Adams, Director 

J. S. Burlew 

Allen Crocker 

J. L. England 

R. E. Gibson 

R. W. Goranson 

J. W. Greig 

Earl Ingerson 

F. C. Kracek 

O. H. Loeffler 

H. E. Merwin 



G. W. Morey 
E. F. Osborn 

C. S. PlGGOT 

Eugene Posnjak 
H. S. Roberts 
J. F. Schairer 

E. S. Shepherd 
George Tunell 
W. D. Urry 

F. E. Wright 
E. G. Zies 



Department of Terrestrial Magnetism 

Organized in 1904; L. A. Bauer, Director 1904-1929 



J. A. Fleming, Director 

O. H. Gish, Assistant Director 

P. H. Abelson 

C. J. Aronson 

L. V, Berkner 

R. C. Coile 

W. Culmsee (resigned) 

S. E. Forbush 

G. K. Green 

L. R. Hafstad 

N. P. Heydenburg 

E. A. Johnson 

H. F. Johnston 

M. W. Jones 

P. G. Ledig 

A. G. McNish 

R. C. Meyer 



W. C. Parkinson 

N. F. Ramsey, Fellow (resigned) 

R. B. Roberts 

W. J. Rooney 

E. Root, 3D 

W. E. Scott 

S. L. Seaton 

K. L. Sherman 

N. M. Smith, Jr., Fellow 

W. F. Steiner 

O. W. TORRESON 

M. A. Tuve 

J. A. Van Allen, Fellow 

E. H. Vestine 

G. R. Wait 

H. W. Wells 



* Retired June 1, 1940 



BIOLOGICAL SCIENCES 



Division of Plant Biology 

Desert Laboratory, opened in 1903, became headquarters of Department of Botanical Research in 1905. 
Name changed to Laboratory for Plant Physiology in 1923; reorganized in 1928 as Division of Plant 
Biology, including Ecology. 



H. A. Spoehr, Chairman 
Jens C. Clausen 
Frederic E. Clements 
William M. Hiesey 
David D. Keck 
Frances L. Long 



Emmett V. Martin 
H. W. Milner 
Forrest Shreve 
James H. C. Smith 
Harold H. Strain 



Department of Embryology 
Organized in 1914; Franklin P. Mall, Director 1914-1917; George L. Streeter, Director 1918 — May 
George W. Corner, Director Chester H. Heuser 



1, 1940 



Robert K. Burns 
Louis B. Flexner 
Alfred Gellhorn, Fellow 
Carl G. Hartman 



Margaret R. Lewis 
* Warren H. Lewis 
f Charles W. Metz 

Herbert A. Pohl 



Department of Genetics 

Station for Experimental Evolution, opened in 1904, combined with Eugenic 
form Department of Genetics. Charles B. Davenport, Director 1904— 1934. 

A. F. Blakeslee, Director B. P. Kaufmann 

M. Demerec, Assistant Director E. C. MacDowell 

Amos G. Avery James S. Potter 

R. W. Bates Oscar Riddle 

A. Dorothy Bergner Sophia Satina 

Katherine S. Brehme, Fellow Morris Steggerda 

Philip N. Bridges, Fellow H. E. Warmke 



Record Office in 1921 to 



Nutrition Laboratory 

Organized in 1907, opened in 1908; F. G. Benedict, Director 1 907-1 937 

T. M. Carpenter, Acting Director Robert C. Lee 

V. Coropatchinsky 



HISTORICAL RESEARCH 

Division of Historical Research 

Department of Historical Research organized in 1903; Andrew C. McLaughlin, Director 1903— 1905, 
J. Franklin Jameson, Director 1 905-1 928. In 1930 this Department was incorporated as the Section of 
United States History in a new Division of Historical Research. 



A. V. Kidder, Chairman 



Section of Aboriginal American History 

Sylvanus G. Morley 
Earl H. Morris 
H. E. D. Pollock 
F. B. Richardson 
Oliver G. Ricketson, Jr. 
Karl Ruppert 
Anna O. Shepard 
Edwin M. Shook 
A. Ledyard Smith 
Robert E. Smith 
Gustav Stromsvik 
Sol Tax 

J. Eric S. Thompson 
Alfonso Villa R. 



Section of Post-Colambian American History 

Eleanor B. Adams 
Robert S. Chamberlain 
Ralph L. Roys 
France V. Scholes 
Leo F. Stock 

Section of the History of Science 

George Sarton 
Alexander Pogo 



* Retired July 1, 1940 
f Resigned July 1, 1940 



RESEARCH ASSOCIATES 

Ernst Antevs, Climatology Charlton M. Lewis, Physics 

Marion E. Blake, Archaeology F. A. Perret, Geophysics 

Barbara S. Burks, Genetics Harry Raymond, Astronomy 

Verne E. Chatelain, History Jack Schultz, Biology 

Paul S. Conger, Biology Harry O. Wood, Seismology 
Newton B. Drury, Study of Primitive Areas S. Yamanouchi, Biology 

Robert Emerson, Biology 

Research Associates Encaged in Post-Retirement Studies 
Frederick H. Seares, Astronomy George L. Streeter, Embryology 

Research Associates Connected with Other Institutions 

Sophie D. Aberle (United States Office of Indian Affairs), Anthropology 

Manuel J. Andrade (University of Chicago), Linguistics 

Ernest B. Babcock (University of California), Genetics 

I. W. Bailey (Harvard University), Plant Biology 

J. Bartels (Forstliche Hochschule, Eberswalde), Terrestrial Magnetism 

Tom. F. W. Barth (University of Oslo), Geophysics 

R. D. Bennett (Massachusetts Institute of Technology), Physics 

V. Bjerknes (University of Oslo), Meteorology 

H. G. Booker (Cambridge University), Terrestrial Magnetism 

Edward L. Bowles (Massachusetts Institute of Technology), Physics 

Joseph C. Boyce (Massachusetts Institute of Technology), Physics 

G. Breit (University of Wisconsin), Physics 

Robert B. Brode (University of California), Physics 

Dirk Brouwer (Yale University), Astronomy 

J. P. Buwalda (California Institute of Technology), Geology and Paleontology 

W. E. Castle (University of California), Biology 

Ralph W. Chaney (University of California), Paleobotany 

S. Chapman (Imperial College, London), Terrestrial Magnetism 

A. H. Compton (University of Chicago), Physics 

L. S. Cressman (University of Oregon), Archaeology 

J. A. Cushman (Cushman Laboratory for Foraminiferal Research), Geophysics 

Th. Dobzhansky (Columbia University), Genetics 

Charles Elton (Oxford University), Climatology 

G. Gamow (George Washington University), Terrestrial Magnetism 

Robert G. Green (University of Minnesota), Biology 

Ross Gunn (United States Naval Research Laboratory), Terrestrial Magnetism 

Arthur T. Hertig (Boston Lying-in Hospital), Embryology 

V. F. Hess (Fordham University), Physics 

Edgar B. Howard (University of Pennsylvania), Archaeology and Paleontology 

J. H. Jeans (Royal Society of London), Astronomy 

Einar Jensen (University of Oslo), Geophysics 

Thomas H. Johnson (Bartol Research Foundation), Physics 

Remington Kellogg (United States National Museum), Paleontology 

S. A. Korff (Bartol Research Foundation), Physics 

E. A. Lowe (The Institute for Advanced Study), Paleography 

C. L. Lundell (University of Michigan), Botany 

Edwin D. McKee (United States National Park Service), Geology and Paleontology 

Robert A. Millikan (California Institute of Technology), Physics 

S. A. Mitchell (University of Virginia), Astronomy 

T. H. Morgan (California Institute of Technology), Biology 

Walter H. Newhouse (Massachusetts Institute of Technology), Geophysics 

Llewellyn I. Price (Harvard University), Paleontology 

Robert Redfield (University of Chicago), Anthropology 

E. G. Ritzman (New Hampshire Agricultural Experiment Station), Nutrition 

Henry A. Ruger (Columbia University), Psychology 

G. Oscar Russell (Ohio State University), Physiology 

Henry N. Russell (Princeton University), Astronomy 



H. C. Sherman (Columbia University), Nutrition 

Alexander Silverman (University of Pittsburgh), Geophysics 

Joel Stebbins (University of Wisconsin), Astronomy 

Chester Stock (California Institute of Technology), Paleontology 

H. U. Sverdrup (Scripps Institute of Oceanography), Terrestrial Magnetism 

M. S. Vallarta (Massachusetts Institute of Technology), Physics 



OFFICES OF ADMINISTRATION 



Office of the President 

Vannevar Bush, President 

Walter M. Gilbert, Executive Officer 

Samuel Callaway, President's Secretary 



Office of Publications and Public Relations 

Theodore H. Dillon, Director 
Dorothy R. Swift, Editorial Assistant 



Office of the Bursar 

*Edmund A. Varela, Bursar 
Earle B. Biesecker, Assistant Bursar 



Investment Office {New Yorf^ City) 

Devereux Josephs, Investment Officer 
Parker Monroe, Investment Officer 



* Retired January i, 1941 



ORGANIZATION, PLAN, AND SCOPE 

The Carnegie Institution of Washington was founded by Andrew Carnegie, January 
28, 1902, when he gave to a board of trustees an endowment of registered bonds of the 
par value of ten million dollars. To this fund an addition of two million dollars was made 
by Mr. Carnegie on December 10, 1907, and a further addition of ten million dollars was 
made by him on January 19, 191 1. Furthermore, the income of a reserve fund of about 
three million dollars, accumulated in accordance with the founder's specifications in 191 1, 
is now available for general use and a sum of five million dollars has been paid by the 
Carnegie Corporation of New York as an increase to the Endowment Fund of the Insti- 
tution, payments having been completed in 1931. The Institution was originally organized 
under the laws of the District of Columbia and incorporated as the Carnegie Institution, 
articles of incorporation having been executed on January 4, 1902. The Institution was 
reincorporated, however, by an act of the Congress of the United States, approved April 
28, 1904, under the title of the Carnegie Institution of Washington. (See existing Articles 
of Incorporation on following pages.) 

Organization under the new Articles of Incorporation was effected May 18, 1904, and 
the Institution was placed under the control of a board of twenty-four trustees, all of whom 
had been members of the original corporation. The trustees meet annually in December 
to consider the affairs of the Institution in general, the progress of work already undertaken, 
and the initiation of new projects, and to make the necessary appropriations for the ensuing 
year. During the intervals between the meetings of the trustees the affairs of the Institution 
are conducted by an Executive Committee chosen by and from the Board of Trustees and 
acting through the President of the Institution as chief executive officer. 

The Articles of Incorporation of the Institution declare in general "that the objects of 
the corporation shall be to encourage, in the broadest and most liberal manner, investi- 
gation, research, and discovery, and the application of knowledge to the improvement of 
mankind." 

The Institution is essentially an operating organization. It attempts to advance funda- 
mental research in fields not normally covered by the activities of other agencies, and to 
concentrate its attention upon specific problems, with the idea of shifting attack from time 
to time to meet the more pressing needs of research as they develop with increase of 
knowledge. Some of these problems require the collaboration of several investigators, 
special equipment, and continuous effort. Many close relations exist among activities of 
the Institution, and a type of organization representing investigations in astronomy, in 
terrestrial sciences, in biological sciences, and in historical research has been effected. Con- 
ference groups on various subjects have played a part in bringing new vision and new 
methods to bear upon many problems. Constant efforts are made to facilitate interpretation 
and application of results of research activities of the Institution, and an Office of 
Publications provides means for appropriate publication. 



ARTICLES OF INCORPORATION 

Public No. 260. An Act to incorporate the Carnegie Institution of Washington 

Be it enacted by the Senate and House of Representatives of the United States of 
America in Congress assembled, That the persons following being persons who are now 
trustees of the Carnegie Institution, namely, Alexander Agassiz, John S. Billings, John L. 
Cadwalader, Cleveland H. Dodge, William N. Frew, Lyman J. Gage, Daniel C. Gilman, 
John Hay, Henry L. Higginson, William Wirt Howe, Charles L. Hutchinson, Samuel P. 
Langley, William Lindsay, Seth Low, Wayne MacVeagh, Darius O. Mills, S. Weir 
Mitchell, William W. Morrow, Ethan A. Hitchcock, Elihu Root, John C. Spooner, Andrew 
D. White, Charles D. Walcott, Carroll D. Wright, their associates and successors, duly 
chosen, are hereby incorporated and declared to be a body corporate by the name of the 
Carnegie Institution of Washington and by that name shall be known and have perpetual 
succession, with the powers, limitations, and restrictions herein contained. 

Sec. 2. That the objects of the corporation shall be to encourage, in the broadest and 
most liberal manner, investigation, research, and discovery, and the application of knowl- 
edge to the improvement of mankind; and in particular — 

(a) To conduct, endow, and assist investigation in any department of science, literature, 
or art, and to this end to cooperate with governments, universities, colleges, technical 
schools, learned societies, and individuals. 

(b) To appoint committees of experts to direct special lines of research. 

(c) To publish and distribute documents. 

(d) To conduct lectures, hold meetings, and acquire and maintain a library. 

(e) To purchase such property, real or personal, and construct such building or buildings 
as may be necessary to carry on the work of the corporation. 

(f) In general, to do and perform all things necessary to promote the objects of the 
institution, with full power, however, to the trustees hereinafter appointed and their 
successors from time to time to modify the conditions and regulations under which the 
work shall be carried on, so as to secure the application of the funds in the manner best 
adapted to the conditions of the time, provided that the objects of the corporation shall 
at all times be among the foregoing or kindred thereto. 

Sec. 3. That the direction and management of the affairs of the corporation and the 
control and disposal of its property and funds shall be vested in a board of trustees, twenty- 
two in number, to be composed of the following individuals: Alexander Agassiz, John S. 
Billings, John L. Cadwalader, Cleveland H. Dodge, William N. Frew, Lyman J. Gage, 
Daniel C. Gilman, John Hay, Henry L. Higginson, William Wirt Howe, Charles L. 
Hutchinson, Samuel P. Langley, William Lindsay, Seth Low, Wayne MacVeagh, Darius 
O. Mills, S. Weir Mitchell, William W. Morrow, Ethan A. Hitchcoc\, Elihu Root, John C. 
Spooner, Andrew D. White, Charles D. Walcott, Carroll D. Wright, who shall constitute 
the first board of trustees. The board of trustees shall have power from time to time to 
increase its membership to not more than twenty-seven members. Vacancies occasioned 
by death, resignation, or otherwise shall be filled by the remaining trustees in such manner 
as the by-laws shall prescribe; and the persons so elected shall thereupon become trustees 



ARTICLES OF INCORPORATION 

and also members of the said corporation. The principal place of business of the said 
corporation shall be the city of Washington, in the District of Columbia. 

Sec. 4. That such board of trustees shall be entitled to take, hold, and administer the 
securities, funds, and property so transferred by said Andrew Carnegie to the trustees of 
the Carnegie Institution and such other funds or property as may at any time be given, 
devised, or bequeathed to them, or to such corporation, for the purposes of the trust; and 
with full power from time to time to adopt a common seal, to appoint such officers, 
members of the board of trustees or otherwise, and such employees as may be deemed 
necessary in carrying on the business of the corporation, at such salaries or with such 
remuneration as they may deem proper; and with full power to adopt by-laws from time 
to time and such rules or regulations as may be necessary to secure the safe and convenient 
transaction of the business of the corporation; and with full power and discretion to deal 
with and expend the income of the corporation in such manner as in their judgment will 
best promote the objects herein set forth and in general to have and use all powers and 
authority necessary to promote such objects and carry out the purposes of the donor. The 
said trustees shall have further power from time to time to hold as investments the securities 
hereinafter referred to so transferred by Andrew Carnegie, and any property which has 
been or may be transferred to them or such corporation by Andrew Carnegie or by any 
other person, persons, or corporation, and to invest any sums or amounts from time to time 
in such securities and in such form and manner as are permitted to trustees or to charitable 
or literary corporations for investment, according to the laws of the States of New York, 
Pennsylvania, or Massachusetts, or in such securities as are authorized for investment by 
the said deed of trust so executed by Andrew Carnegie, or by any deed of gift or last will 
and testament to be hereafter made or executed. 

Sec. 5. That the said corporation may take and hold any additional donations, grants, 
devises, or bequests which may be made in further support of the purposes of the said 
corporation, and may include in the expenses thereof the personal expenses which the 
trustees may incur in attending meetings or otherwise in carrying out the business of the 
trust, but the services of the trustees as such shall be gratuitous. 

Sec. 6. That as soon as may be possible after the passage of this Act a meeting of the 
trustees hereinbefore named shall be called by Daniel C. Gilman, John S. Billings, Charles 
D. Walcott, S. Weir Mitchell, John Hay, Elihu Root, and Carroll D. Wright, or any four 
of them, at the city of Washington, in the District of Columbia, by notice served in person 
or by mail addressed to each trustee at his place of residence; and the said trustees, or a 
majority thereof, being assembled, shall organize and proceed to adopt by-laws, to elect 
officers and appoint committees, and generally to organize the said corporation; and said 
trustees herein named, on behalf of the corporation hereby incorporated, shall thereupon 
receive, take over, and enter into possession, custody, and management of all property, 
real or personal, of the corporation heretofore known as the Carnegie Institution, incorpo- 
rated, as hereinbefore set forth under "An Act to establish a Code of Law for the District 
of Columbia, January fourth, nineteen hundred and two," and to all its rights, contracts, 
claims, and property of any kind or nature; and the several officers of such corporation, or 
any other person having charge of any of the securities, funds, real or personal, books, or 
property thereof, shall, on demand, deliver the same to the said trustees appointed by this 
Act or to the persons appointed by them to receive the same; and the trustees of the existing 



CARNEGIE INSTITUTION OF WASHINGTON 

corporation and the trustees herein named shall and may take such other steps as shall be 
necessary to carry out the purposes of this Act. 

Sec. 7. That the rights of the creditors of the said existing corporation known as the 
Carnegie Institution shall not in any manner be impaired by the passage of this Act, or 
the transfer of the property hereinbefore mentioned, nor shall any liability or obligation for 
the payment of any sums due or to become due, or any claim or demand, in any manner 
or for any cause existing against the said existing corporation, be released or impaired; 
but such corporation hereby incorporated is declared to succeed to the obligations and 
liabilities and to be held liable to pay and discharge all of the debts, liabilities, and contracts 
of the said corporation so existing to the same effect as if such new corporation had itself 
incurred the obligation or liability to pay such debt or damages, and no such action or 
proceeding before any court or tribunal shall be deemed to have abated or been discontinued 
by reason of the passage of this Act. 

Sec. 8. That Congress may from time to time alter, repeal, or modify this Act of 
incorporation, but no contract or individual right made or acquired shall thereby be 
divested or impaired. 

Sec. 9. That this Act shall take effect immediately. 

Approved, April 28, 1904 



BY-LAWS OF THE INSTITUTION 

Adopted December 13, 1904. Amended December 13, 1910, December 13, 1912, 
December 10, 1937, December 15, 1939, and December 13, 1940 

Article I 

THE TRUSTEES 

i. The Board of Trustees shall consist of twenty-four members, with power to increase 
its membership to not more than twenty-seven members. The Trustees shall hold office 
continuously and not for a stated term. 

2. In case any Trustee shall fail to attend three successive annual meetings of the Board 
he shall thereupon cease to be a Trustee. 

3. No Trustee shall receive any compensation for his services as such. 

4. All vacancies in the Board of Trustees shall be filled by the Trustees by ballot. Sixty 
days prior to an annual or a special meeting of the Board, the President shall notify the 
Trustees by mail of the vacancies to be filled and each Trustee may submit nominations 
for such vacancies. A list of the persons so nominated, with the names of the proposers, 
shall be mailed to the Trustees thirty days before the meeting, and no other nominations 
shall be received at the meeting except with the unanimous consent of the Trustees present. 
Vacancies shall be filled from the persons thus nominated, but no person shall be declared 
elected unless he receives the votes of two-thirds of the Trustees present. 

Article II 

MEETINGS 

1. The annual meeting of the Board of Trustees shall be held in the City of Washington, 
in the District of Columbia, on the first Friday following the second Thursday of December 
in each year. 

2. Special meetings of the Board may be called by the Executive Committee by notice 
served personally upon, or mailed to the usual address of, each Trustee twenty days prior 
to the meeting. 

3. Special meetings shall, moreover, be called in the same manner by the Chairman upon 
the written request of seven members of the Board. 

Article III 

OFFICERS OF THE BOARD 

i. The officers of the Board shall be a Chairman of the Board, a Vice-Chairman, and 
a Secretary, who shall be elected by the Trustees, from the members of the Board, by ballot 
to serve for a term of three years. All vacancies shall be filled by the Board for the 
unexpired term; provided, however, that the Executive Committee shall have power to fill 
a vacancy in the office of Secretary to serve until the next meeting of the Board of Trustees. 

2. The Chairman shall preside at all meetings and shall have the usual powers of a 
presiding officer. 



CARNEGIE INSTITUTION OF WASHINGTON 

3. The Vice-Chairman, in the absence or disability of the Chairman, shall perform 
his duties. 

4. The Secretary shall issue notices of meetings of the Board, record its transactions, and 
conduct that part of the correspondence relating to the Board and to his duties. 

Article IV 

EXECUTIVE ADMINISTRATION 

The President 

1. There shall be a President who shall be elected by ballot by, and hold office during 
the pleasure of, the Board, who shall be the chief executive officer of the Institution. The 
President, subject to the control of the Board and the Executive Committee, shall have 
general charge of all matters of administration and supervision of all arrangements for 
research and other work undertaken by the Institution or with its funds. He shall devote 
his entire time to the affairs of the Institution. He shall prepare and submit to the Board 
of Trustees and to the Executive Committee plans and suggestions for the work of the 
Institution, shall conduct its general correspondence and the correspondence with applicants 
for grants and with the special advisers of the Committee, and shall present his recom- 
mendations in each case to the Executive Committee for decision. All proposals and 
requests for grants shall be referred to the President for consideration and report. He 
shall have power to remove and appoint subordinate employees and shall be ex officio a 
member of the Executive Committee. 

2. He shall be the legal custodian of the seal and of all property of the Institution whose 
custody is not otherwise provided for. He shall sign and execute on behalf of the corpora- 
tion all contracts and instruments necessary in authorized administrative and research 
matters and affix the corporate seal thereto when necessary, and may delegate the per- 
formance of such acts and other administrative duties in his absence to the Executive 
Officer. He may execute all other contracts, deeds, and instruments on behalf of the 
corporation and affix the seal thereto when expressly authorized by the Board of Trustees 
or Executive Committee. He may, within the limits of his own authorization, delegate to 
the Executive Officer authority to act as custodian of and affix the corporate seal. He shall 
be responsible for the expenditure and disbursement of all funds of the Institution in 
accordance with the directions of the Board and of the Executive Committee, and shall 
keep accurate accounts of all receipts and disbursements. He shall submit to the Board of 
Trustees at least one month before its annual meeting in December a written report of the 
operations and business of the Institution for the preceding fiscal year with his recom- 
mendations for work and appropriations for the succeeding fiscal year, which shall be 
forthwith transmitted to each member of the Board. 

3. He shall attend all meetings of the Board of Trustees. 

4. There shall be an officer designated Executive Officer who shall be appointed by and 
hold office at the pleasure of the President, subject to the approval of the Executive 
Committee. His duties shall be to assist and act for the President as the latter may duly 
authorize and direct. 

5. The President shall retire from office at the end of the calendar year in which he 
becomes sixty-five years of age. 



BY-LAWS OF THE INSTITUTION 
Article V 

COMMITTEES 

i. There shall be the following standing Committees, viz. an Executive Committee, a 
Finance Committee, and an Auditing Committee. 

2. The Executive Committee shall consist of the Chairman and Secretary of the Board 
of Trustees and the President of the Institution ex officio and, in addition, five trustees 
to be elected by the Board by ballot for a term of three years, who shall be eligible for 
re-election. Any member elected to fill a vacancy shall serve for the remainder of his 
predecessor's term: Provided, however, that of the Executive Committee first elected after 
the adoption of these by-laws two shall serve for one year, two shall serve for two years, 
and one shall serve for three years; and such Committee shall determine their respective 
terms by lot. 

3. The Executive Committee shall, when the Board is not in session and has not given 
specific directions, have general control of the administration of the affairs of the corpora- 
tion and general supervision of all arrangements for administration, research, and other 
matters undertaken or promoted by the Institution; shall appoint advisory committees for 
specific duties; shall determine all payments and salaries; and keep a written record of all 
transactions and expenditures and submit the same to the Board of Trustees at each 
meeting, and it shall also submit to the Board of Trustees a printed or typewritten report 
of each of its meetings, and at the annual meeting shall submit to the Board a report for 
publication. The Executive Committee shall have power to authorize the purchase, sale, 
exchange, or transfer of real estate. 

4. The Executive Committee shall have general charge and control of all appropriations 
made by the Board. 

5. The Finance Committee shall consist of five members to be elected by the Board of 
Trustees by ballot for a term of three years. 

6. The Finance Committee shall have custody of the securities of the corporation and 
general charge of its investments and invested funds, and shall care for and dispose of the 
same subject to the directions of the Board of Trustees. It shall have power to authorize 
the purchase, sale, exchange, or transfer of securities and to delegate this power. It shall 
consider and recommend to the Board from time to time such measures as in its opinion 
will promote the financial interests of the Institution, and shall make a report at each 
meeting of the Board. 

7. The Auditing Committee shall consist of three members to be elected by the Board 
of Trustees by ballot for a term of three years. 

8. The Auditing Committee shall, before each annual meeting of the Board of Trustees, 
examine the accounts of business transacted under the Finance Committee and the Execu- 
tive Committee. They may avail themselves at will of the services and examination of the 
Auditor appointed by the Board of Trustees. They shall report to the Board upon the 
collection of moneys to which the Institution is entitled, upon the investment and reinvest- 
ment of principal, upon the conformity of expenditures to appropriations, and upon the 
system of bookkeeping, the sufficiency of the accounts, and the safety and economy of the 
business methods and safeguards employed. 

9. All vacancies occurring in the Executive Committee and the Finance Committee shall 
be filled by the Trustees at the next regular meeting. In case of vacancy in the Finance 
Committee or the Auditing Committee, upon request of the remaining members of such 



CARNEGIE INSTITUTION OF WASHINGTON 

committee, the Executive Committee may fill such vacancy by appointment until the next 
meeting of the Board of Trustees. 

10. The terms of all officers and of all members of committees shall continue until their 
successors are elected or appointed. 

Article VI 

FINANCIAL ADMINISTRATION 

i. No expenditure shall be authorized or made except in pursuance of a previous appro- 
priation by the Board of Trustees, or as provided in Article V, paragraph 6, hereof. 

2. The fiscal year of the Institution shall commence on the first day of November in 
each year. 

3. The Executive Committee, at least one month prior to the annual meeting in each 
year, shall cause the accounts of the Institution to be audited by a skilled accountant, to 
be appointed by the Board of Trustees, and shall submit to the annual meeting of the 
Board a full statement of the finances and work of the Institution and a detailed estimate 
of the expenditures of the succeeding year. 

4. The Board of Trustees, at the annual meeting in each year, shall make general appro- 
priations for the ensuing fiscal year; but nothing contained herein shall prevent the Board 
of Trustees from making special appropriations at any meeting. 

5. The securities of the Institution and evidences of property, and funds invested and to 
be invested, shall be deposited in such safe depository or in the custody of such trust 
company and under such safeguards as the Trustees and Finance Committee shall desig- 
nate; and the income available for expenditure of the Institution shall be deposited in such 
banks or depositories as may from time to time be designated by the Executive Committee. 

6. Any trust company entrusted with the custody of securities by the Finance Committee 
may, by resolution of the Board of Trustees, be made Fiscal Agent of the Institution, upon 
an agreed compensation, for the transaction of the business coming within the authority 
of the Finance Committee. 

Article VII 

AMENDMENT OF BY-LAWS 

i. These by-laws may be amended at any annual or special meeting of the Board of 
Trustees by a two-thirds vote of the members present, provided written notice of the 
proposed amendment shall have been served personally upon, or mailed to the usual 
address of, each member of the Board twenty days prior to the meeting. 



ABSTRACT OF MINUTES OF THE FORTY-SECOND MEETING 
OF THE BOARD OF TRUSTEES 

The meeting was held in Washington in the Board Room of the Administration 
Building on Friday, December 13, 1940. It was called to order at 10:00 a.m. by the 
Chairman, Mr. Forbes. 

Upon roll call, the following Trustees responded: Thomas Barbour, James F. Bell, 
Frederic A. Delano, W. Cameron Forbes, Walter S. GifTord, Walter A. Jessup, Roswell 
Miller, Henry S. Morgan, Stewart Paton, John J. Pershing, Elihu Root, Jr., Henry R. 
Shepley, Richard P. Strong, Charles P. Taft, James W. Wadsworth, Frederic C. Walcott, 
and Lewis H. Weed. The President of the Institution, Dr. Vannevar Bush, was also in 
attendance. 

The minutes of the forty-first meeting were approved as printed and submitted to the 
members of the Board. 

Reports of the President, the Executive Committee, the Auditor, the Finance Committee, 
the Auditing Committee, and of Chairmen of Divisions, Directors of Departments, and 
Research Associates of the Institution were presented and considered. 

The following appropriations for the year 1941 were authorized: 

Pension Fund $60,000 

Administration 1 16,560 

Publications (including Office of Publications and Public Relations) . . 67,580 

Departmental Research Operations 1,011,467 

Research Projects of Limited Tenure 80,000 

$1,335,607 

The Chairman reported the death of William Benson Storey, and presented the resigna- 
tion of Charles A. Lindbergh, which was accepted with regret. With unanimous consent 
the Trustees proceeded to the election of new members. As a result of balloting, Lindsay 
Bradford, President of the City Bank Farmers Trust Company, New York City, and 
Dr. Seeley G. Mudd, of California Institute of Technology, were elected to fill existing 
vacancies in the Board. 

Upon recommendation of the Executive Committee, Article V, Section 3, of the By-Laws 
of the Institution was amended to read as follows: 

Article V 

COMMITTEES 

3. The Executive Committee shall, when the Board is not in session and has not given specific 
directions, have general control of the administration of the affairs of the corporation and general 
supervision of all arrangements for administration, research, and other matters undertaken or 
promoted by the Institution; shall appoint advisory committees for specific duties; shall determine 
all payments and salaries; and keep a written record of all transactions and expenditures and 
submit the same to the Board of Trustees at each meeting, and it shall also submit to the Board 
of Trustees a printed or typewritten report of each of its meetings, and at the annual meeting 
shall submit to the Board a report for publication. The Executive Committee shall have power 
to authorize the purchase, sale, exchange, or transfer of real estate. 



CARNEGIE INSTITUTION OF WASHINGTON 

Mr. Gifford reported that the Executive Committee, at its meeting of November 8, 1940, 
voted the following resolution: 

"Resolved, That the President of the Carnegie Institution of Washington be authorized to 
cooperate in the national defense program, and to tender to the United States Government the 
services of members of departmental and divisional staffs of the Institution, together with equip- 
ment and laboratory facilities; and that the President, in his discretion, be empowered to comply 
with requests from the U. S. Government for services of the Institution, to accept reimbursement 
from the Government for such expenses as are met by advance of Institution funds, and to take 
necessary steps for leaves of absence, with assurance of appropriate compensation and maintenance 
of status, for staff members who may enlist in the military service of the Government, who may 
be called for training or selective service by the Government, or who may be engaged in other 
service in connection with national defense." 

In support of this action, it was 

Resolved, That the Board of Trustees formally and specifically record its approval of the action 
of the Executive Committee at its meeting of November 8, 1940, providing for full cooperation 
of the Institution in the national defense program. 

The meeting adjourned at 12:00 noon. 



REPORT OF THE EXECUTIVE COMMITTEE 

For the Year Ending October 31, 1940 

To the Trustees of the Carnegie Institution of Washington: 

Gentlemen: Article V, section 3 of the By-Laws provides that the Executive Committee 
shall submit, at the annual meeting of the Board of Trustees, a report for publication; and 
Article VI, section 3, provides that the Executive Committee shall also submit, at the same 
time, a full statement of the finances and work of the Institution and a detailed estimate of 
the expenditures for the succeeding year. In accordance with these provisions, the Executive 
Committee herewith respectfully submits its report for the fiscal year ending October 
31, 1940. 

During this year the Executive Committee held six meetings, printed reports of which 
have been mailed to each Trustee and constitute a part of this report. 

A full statement of the work of the Institution is contained in the report of the President, 
which has been considered and approved by the Executive Committee, and is submitted 
herewith. A detailed estimate of expenditures for the succeeding year is also contained in 
the report of the President, and has been considered by the Executive Committee, which 
has approved the recommendations of the President in respect thereto and has provisionally 
approved the budget estimates based thereon and submitted therewith. Close attention 
has been given both by the Executive Committee and by the Finance Committee to the 
question of availability of funds for Institution activities in 1941, and budget recommenda- 
tions are based upon the judgment of these Committees with respect to financial policy in a 
period of reduced income. 

The Board of Trustees, at its meeting of December 15, 1939, appointed Arthur Young 
and Company to audit the accounts of the Institution for the fiscal year ending October 
31, 1940. The report of the Auditor, including a balance sheet showing assets and 
liabilities of the Institution on October 31, 1940, is submitted as a part of the report of the 
Executive Committee. 

In addition to the report of the Auditor there is also submitted a financial statement for 
the fiscal year ending October 31, 1940, showing funds available for expenditure and 
amounts allotted by the Executive Committee, and a customary statement of receipts and 
disbursements since the organization of the Institution on January 28, 1902. These state- 
ments together with the tables in the Auditor's report comprise a full statement of the 
finances of the Institution. 

A vacancy exists in the membership of the Board of Trustees, and also of its Auditing 
Committee, by reason of the death of William Benson Storey on October 24, 1940. There 
are no vacancies in the membership of the Executive Committee or Finance Committee. 

W. Cameron Forbes, Chairman 
Robert Woods Bliss 
Vannevar Bush 
Frederic A. Delano 
Walter S. Gifford 
Walter A. Jessup 
Frederic C. Walcott 
November 8, 1940 Lewis H. Weed 

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REPORT OF AUDITORS 

To the Board of Trustees 
Carnegie Institution of Washington 
Washington, D. C. 

We have made an examination of the books and accounts of Carnegie Institution of 
Washington for the year ended October 31, 1940. 

Income from investments and other sources has been duly accounted for and all dis- 
bursements were evidenced by paid voucher checks and/or properly approved invoices. 
The cash and securities were verified by certificates received from depositories and custo- 
dians. As in past years, the detail accounts of the Departments of Research in the field 
have been audited by the Bursar of the Institution, and we are of the opinion, as a result 
of reviewing the internal audit methods in force, that such internal audit is satisfactorily 
conducted. 

The securities are stated at cost or value at date acquired, this being the established 
custom of the Institution. However, in accordance with a recommendation made in 
February 1940 by the Institution's Finance Committee, all premiums on all obligations 
purchased subsequent to January 1, 1940 are being amortized on a straight-line basis to 
the end of the calendar year last preceding the date on which an obligation is first callable 
or payable at par. The amortization of the premiums applicable to the ten months ended 
October 31, 1940 amounted to $7,777.97 and has been deducted from the cost of such 
obligations. 

Real estate and equipment are stated at original cost and books on hand for sale at their 
sales prices. 

We inspected certified copies of the minutes of the meetings of the Board of Trustees and 
Executive Committee as authority for the appropriations and allotments made during 
the year. 

In our opinion, on the basis of valuations stated above, the accompanying balance sheet, 
statement of receipts and disbursements, and detailed schedule of securities properly present 
the financial position of the Carnegie Institution of Washington at October 31, 1940 and 
the transactions for the year ended that date. 

Arthur Young & Company 
Accountants and Auditors 
New Yor{, N. Y. 
November 27, 1940 



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Schedule of Securities 



Aggregate — 

par or 
nominal value 



Description 



Ma- 
turity 



Cost, amortized 

cost, or 

value at date 

acquired 



$300,000 
300,000 
300,000 
240,000 
815,000 
300,000 



United States Government Bonds 



U. S. Guar. Federal Farm Mtg. Corp., 3s. 
U. S. Guar. Home Owners Loan Corp., 1 } 

U. S. of America Treasury, 2s 

U. S. of America Treasury, 2s 

U. S. of America Treasury, 2 Ms 

U. S. of America Treasury, 2 Ms 



1949-44 
1947-45 

1947 
1950-48 
1956-54 

1948 



$321, 492. 18* 
304,134.38* 
312,796.88* 
240,000.00 
834,218.75 
320,589.84* 



$2,255,000 



Total U. S. Government 



$2,333,232.03 



$50,000 
25,000 
25,000 
50,000 

230,100 
50,000 
84,000 
50,000 



State and Municipal Bonds 



City of Cleveland, Cuyahoga County, Water Works, $}4s 

City of Detroit, Water Supply, 4s 

City of Detroit, Water Supply, 4 Ms 

City of Newark, New Jersey, Street Opening, 5 Ms 

City of New York, Corporate Stock, 3s 

City of New York, Corporate Stock, 4 Ms 

State of North Carolina, Highway, serial 4 'is ($30,000 registered) 
City and County of San Francisco, Hetch Hetchy, 5 Ms 



1967 
1955 
1952 
1958 
1980 
1957 
1953-63 
1960 



$52,984.60 
24,812.50 
25,250.00 
51,724.94 

218,595.00 
58,531.25 
92,819.50 
53,523.34 



$564,100 



$55,000 
100,000 
100,000 

91,000 
105,500 
100,000 
100,000 
150,000 
100,000 
100,000 

40,000 
250,000 
100,000 

90,000 



Total State and Municipal 



$578,241.13 



Foreign Bonds 



Dominion of Canada, 5s 

Canadian National Ry. Co., 4 Ms, guar 

Canadian National Ry. Co., 5s, guar 

Canadian Pacific Ry. Co., coll. trust 5s 

German External Loan of 1924, 7s, std 

Province of Alberta, deb. 4 Ms 

Province of Alberta, deb. 5s 

Province of Manitoba, deb. 4 Ms 

Province of Nova Scotia, deb. 4 Ms 

Province of Ontario, deb. 4s 

Province of Ontario, deb. 6s 

Shawinigan Water and Power Co., 1st mtg. and coll. trust s. f. 4 Ms 

City of Toronto, cons, loan deb. 5s 

City of Toronto, deb. 5s 



1952 
1957 
1969 
1954 
1949 
1958 
1950 
1958 
1952 
1964 
1943 
1967 
1949 
1952 



$60,450.00 

112,000.00 

98 , 500 . 00 

90,835.11 

112,713.00 

93,750.00 

101,150.00 

142,886.77 

100,312.50 

87,150.10 

43,137.50 

238,510.42 

96,164.59 

89,333.53 



$1,481,500 



Total Foreign 



$1,466,893.52 



$100,000 

231,000 

129,000 

300,000 

300,000 

75,000 

380,000 

23,900 

83,000 

50,000 

40,000 

100,000 

325,000 

200,000 

25,000 

200,000 

25 , 000 

150,000 

100,000 

100,000 

50,000 

100,000 

100,000 

65,000 

47,000 

18,000 

10,000 

50,000 

100,000 



Public Utility Bonds 

Alabama Power Co., 1st and ref. mtg. 4 Ms 

Alabama Power Co., 1st and ref. mtg. 5s 

American Gas & Electric Co., s. f. deb. 2 Ms 

Appalachian Electric Power Co., 1st mtg. 4s 

Arkansas Power & Light Co., 1st and ref. mtg. 5s 

Blackstone Valley Gas & Electric Co., mtg. and coll. trust 4s 

Columbia Gas & Electric Corp., deb. 5s 

Commonwealth Edison Co., conv. deb. 3 Ms 

Commonwealth Edison Co., 1st mtg. 3 Ms 

Consolidated Edison Co. of N. Y., deb. 3 Ms 

Consolidated Edison Co. of N. Y., deb. 3 Ms 

Detroit Edison Co., gen. and ref. mtg. 4s 

Georgia Power Co., 1st ref. mtg. 5s 

Gulf States Utilities Co., 1st mtg. and ref. 3 Ms 

Houston Lighting & Power Co., 1st mtg. 3 Ms 

Illinois Power & Light Corp., 1st and ref. mtg. 5s 

Lone Star Gas Corp., s. f. deb. 3 Ms 

Louisiana Power & Light Co., 1st mtg. 5s 

Metropolitan Edison Co., 1st mtg. 4 Ms 

Minnesota Power & Light Co., 1st and ref. mtg. 4 Ms 

Monongahela West Penn Public Service Co., 1st mtg. 4 Ms.. 

Montana Power Co., 1st and ref. mtg. 3 Ms 

New Orleans Public Service Co., 1st and ref. mtg. 5s 

New York & Westchester Lighting Co., deb. 5s 

North American Co., deb. 3 Ms 

North American Co., deb. 3 Ms 

North American Co., deb. 4s 

Northern States Power Co., 1st and ref. mtg. 3 Ms 

Ohio Edison Co., 1st mtg. 4s 

(Continued on following page) 



1967 
1968 
1950 
1963 
1956 
1965 
1961 
1958 
1968 
1948 
1958 
1965 
1967 
1969 
1966 
1956 
1953 
1957 
1968 
1978 
1960 
1966 
1955 
1954 
1949 
1954 
1959 
1967 
1967 



$87,265.00 

219,516.25 

131,902.50* 

296,250.00 

292,312.50 

76,875.00 

379,762.50 

23,910.75 

85,712.87 

50,875.00 

40,730.00 

103,500.00 

320,112.50 

213,500.00 

25,750.00 

196,750.00 

26,406.25 

154,900.00 

109,470.00 

92,156.25 

52,000.00 

101,000.00 

99,200.00 

67,052.50 

47,822.50 

18,180.00 

10,125.00 

47,500.00 

100,266.25 



* Includes deduction for amortization of premiums on bonds purchased subsequent to January 1, 1940. Amortization 
is on a straight-line basis to end of calendar year last preceding date on which bonds are first callable or payable at par. 



Schedule of Securities — Continued 



Aggregate- 
par or 
nominal value 



Description 



Ma- 
turity 



Cost, amortized 

cost, or 

value at date 

acquired 



$100,000 
100,000 
200,000 
98 , 000 
100,000 
100,000 
200,000 
141,000 
60,000 
50,000 
300,000 
195,500 
120,000 
250,000 
220,000 
263,000 
225,000 



Public Utility Bonds — Continued 



Ohio Power Co., 1st mtg. 3 >+s 

Ohio Public Service Co., 1st mtg. 4s 

Oklahoma Gas & Electric Co., 1st mtg. 3 a<s 

Oklahoma Natural Gas Co., 1st. mtg. 3 Hs 

Pacific Gas & Electric Co., 1st and ref. mtg. 3 J^s 

Pacific Gas & Electric Co., 1st and ref. mtg. 4s 

Pennsylvania Electric Co., 1st and ref. mtg. 5s 

Public Service Co. of Northern Illinois, 1st mtg. 3Ks . . . 
Puget Sound Power & Light Co., 1st and ref. mtg. 4Ks. 
Puget Sound Power & Light Co., 1st and ref. mtg. 5Ks. 

Texas Electric Service Co., 1st mtg. 5s 

Texas Power & Light Co., 1st and ref. mtg. 5s 

Toledo Edison Co., 1st mtg. 3 Ks 

Union Electric Co. of Missouri, 1st mtg. coll. trust 3 J 4 s. 

Utah Light & Traction Co., 1st and ref. mtg. 5s 

Virginia Electric & Power Co., 1st and ref. mtg. 3}4s. . . . 
Wisconsin Electric Power Co., 1st mtg. 3 }4s 



1968 
1962 
1966 
1955 
1961 
1964 
1962 
1968 
1950 
1949 
1960 
1956 
1968 
1962 
1944 
1968 
1968 



$101 
102 
205 
105 
102 
104 
203 
145 
56 
31 
292 
200 
121 
249 
215 
272 
232 



,500.00 
,625.00 
,000.00 
,585.20 
,500.00 
,000.00 
,882.50 
,230.00 
,550.00 
,900.00 
,700.00 
,528.02 
,800.00 
,537.50 
,193.00 
,205.00 
,875.00 



$6,199,400 



Total Public Utility . 



i, 214, 414. 



$51,000 

314,000 

125,000 

25,000 

52,000 

75,000 



Communication Bonds 



American Telephone & Telegraph Co., deb. 3 yis 

American Telephone & Telegraph Co., deb. 3Ks 

American Telephone & Telegraph Co., s. f. deb. 5 yis. . . 
Mountain States Telephone & Telegraph Co., deb. 3 '(s. 
New England Telephone & Telegraph Co., 1st mtg. 5s. . 
Southern Bell Telephone & Telegraph Co., deb. 3}{s. . . . 



1961 
1966 
1943 
1968 
1952 
1962 



$51,510.00 

326,706.75 

130,260.62 

25,500.00 

51,748.00 

72,375.00 



$642,000 



Total Communications . 



$658,100.37 



$90,000 
120,000 
100,000 



Railroad Equipment Trusts 



Erie R. R. Co., 4 !-<s, guar 

Illinois Central R. R. Co., 4Ks.. 
Missouri Pacific R. R. Co., 4Ks. 



1942-43 
1942-44 
1941-42 



$86,467.90 
115,184.84 
95,849.61 



$310,000 



Total Railroad Equipment Trusts . 



$297,502.35 



$200,000 

27,000 

100,000 

50,000 

100,000 

189,000 

35,000 

140,000 

234,000 

120,000 

200,000 

300,000 

75,000 

300,000 

50,000 

100,000 

45,000 

30,000 

200,000 

225,000 

150,000 

50,000 

213,000 

50,000 

50,000 

50,000 

75,000 

100,000 

50,000 

42,000 

100,000 



Railroad Bonds 

Atchison, Topeka & Santa Fe Ry. Co., 1st and ref. mtg. i l As 

Baltimore & Ohio R. R. Co., ref. mtg. 4s, std 

Baltimore & Ohio R. R. Co., 1st mtg. 4-5s 

Central Pacific Ry. Co., 1st ref. mtg. 4s, guar 

Chesapeake & Ohio Ry. Co., gen. mtg. 4Ks 

Chicago, Indianapolis & Louisville Ry. Co., 1st and gen. mtg. 5s 

Chicago, Milwaukee, St. Paul & Pacific R. R. Co., 5s 

Chicago, Milwaukee, St. Paul & Pacific R. R. Co., conv. adj. mtg. 5s. 

Chicago, Milwaukee & St. Paul Ry. Co., gen. mtg. 4 yia 

Chicago & North Western Ry. Co., gen. mtg. 3 Ks 

Chicago & North Western Ry. Co., gen. mtg. 4 3<is 

Chicago, Rock Island & Pacific Ry. Co., 4Ks, secured std 

Chicago & Western Indiana R. R. Co., cons. 4s 

Erie R. R. Co., gen. lien 4s 

Great Northern Ry. Co., 1st and ref. mtg. 4 J4S, std 

Great Northern Ry. Co., gen. mtg. 5s 

Gulf, Mobile & Ohio R. R. Co., 1st and ref. mtg. 4s 

Gulf, Mobile, & Ohio R. R. Co., gen. mtg. income 5s 

Kansas City, Fort Scott & Memphis Ry., ref. mtg. 4s (Ctf. of Deposit) 

Lehigh & Lake Erie R. R. Co., 1st mtg. lyis 

Louisville & Nashville R. R. Co., 1st and ref. mtg. 4Ks 

Missouri, Kansas & Texas Ry. Co., 1st mtg. 4s 

Missouri Pacific R. R. Co., 1st and ref. mtg. 5s 

New York, Pennsylvania & Ohio R. R. Co., prior lien 4Ks 

New York, Westchester & Boston Ry. Co., 1st mtg. 4 Ms 

Oregon Short Line R. R. Co., cons. 1st mtg. 5s 

Pennsylvania R. R. Co., gen. mtg. 4 Ks 

Pennsylvania R. R. Co., cons. mtg. 4}4s 

Pittsburgh, Cincinnati, Chicago & St. Louis R. R. Co., gen. mtg. 5s, guar. 
Pittsburgh, Shawmut& Northern R. R. Co., ref . 1st mtg. 4s(Ctf . of Deposit) 
Southern Ry. Co., 1st cons. mtg. 5s 

(.Continued on following page) 



1962 
1951 
1948 
1949 
1992 
1966 
1975 
2000 
1989 
1987 
1987 
1952 
1952 
1996 
1961 
1973 
1975 
2015 
1936 
1957 
2003 
1990 
1977 
1950 
1946 
1946 
1965 
1960 
1975 
1952 
1994 



$199,500.00 

25,312.50 

105,700.00 

48,250.00 

99,464.29 

189,461.25 

31,853.50 

127,414.50 

227,162.50 

100,300.00 

210,000.00 

280,964.50 

70,357.66 

242,937.50 

50,113.59 

104,385.84 

27,450.00 

10,875.00 

187,250.00 

229,547.29 

149,475.00 

41,301.56 

212,762.50 

52,500.00 

49,187.50 

48,405.15 

75,918.75 

104,662.50 

51,898.98 

4,200.00 

103,580.34 



Schedule of Securities — Continued 



Aggregate — 

par or 
nominal value 



Description 



Ma- 
turity 



Cost, amortized 

cost, or 

value at date 

acquired 



$225,000 

70,000 

100,000 

2,084,000 

100,000 

40,000 

200,000 

100,000 

50,000 



Railroad Bonds — Continued 

St. Louis-San Francisco Ry. Co., prior lien mtg. 4s (Ctf. of Deposit) . 

Terminal R. R. Assn. of St. Louis, s. f. gen. ref. mtg. 4s 

Toledo & Ohio Central Ry. Co., ref. and imp. mtg. 3 Ms, guar 

Union R. R. Co., deb. 6s, guar 

Virginian Ry. Co., 1st lien and ref. mtg. 3 Ms 

Wabash R. R. Co., 1st mtg. 5s 

Wabash Ry. Co., ref. and gen. mtg. 5s 

West Shore R. R. Co., 1st mtg. 4s, guar 

Western Maryland Ry. Co., 1st and ref. mtg. 5 Ms 



1950 
1953 
1960 
1946 
1966 
1939 
1976 
2361 
1977 



$203,431.25 

63,603.92 

99,000.00 

2,084,000.00 

102,250.00 

37,750.00 

203,250.00 

78,140.00 

42,677.19 



$6,619,000 



Total Railroad . 



,376,294.56 



$50,000 

50,000 

150,000 

227,000 

5,000 

140,000 

100,000 

99,000 

96,000 

100,000 

400,000 

75,000 

53,000 

100,000 

,925,000 

200.000 
85,000 
98,000 



Industrial and Miscellaneous Bonds 

Allis-Chalmers Mfg. Co., conv. s. f. deb. 4s 

Atlantic Refining Co., deb. 3s 

Bethlehem Steel Corp., conv. s. f. deb. 3 Ms 

Loew's Incorporated, s. f . deb. 3 Ms 

Phelps Dodge Corp., conv. deb. 3 Ms 

Railway Express Agency, serial notes 1 Ms-2 Ms 

Remington Rand, Inc., deb. 4 Ms, w. w 

Republic Steel Corp., gen. mtg. 4 Ms 

Republic Steel Corp., gen. mtg. 4 Ms 

Scovill Manufacturing Co., deb. 3 Ms 

Shell Union Oil Corp., deb. 2 Ms 

Socony Vacuum Oil Co., deb. 3s 

Southern Kraft Corp., 1st leasehold and gen. mtg. 4 Ms 

Standard Oil Co. of N. J., deb. 2 Ms 

Tennessee Coal, Iron & R. R. Co., gen. mtg. 5s (payment guaranteed 

by U. S. Steel Corp.) 

West Virginia Pulp & Paper Co., 1st mtg. 3s 

Wheeling Steel Corp., 1st mtg. s. f. 4Ms 

Youngstown Sheet & Tube Co., 1st mtg. s. f . 4s 



1952 
1953 
1952 
1946 
1952 
1942-48 
1956 
1956 
1961 
1950 
1954 
1964 
1946 
1953 

1951 
1954 
1966 
1961 



$51,587.00 

51,187.50 

148,750.00 

232,963.15 

5,000.00 

140,000.00 

100,162.50 

103,337.50 

99,587.50 

102,000.00 

384,176.25 

78,000.00 

51,790.00 

99,000.00 

1,925,000.00 
198,000.00 
86,275.00 
96,530.00 



$3,953,000 



Total Industrial and Miscellaneous . 



$3,953,346.40 



$98,482.13 
100,000 

80,000 

95,261.23 

90,000 
97,000 
90,000 



Mortgages 

Lawyers Mtg. Co., Guaranteed 1st Mtg. Ctfs.. Series 18397T, 4% 

Lawyers Mtg. Co., Guaranteed 1st Mtg. Ctfs., 4M%- No. 29940T 

Lawyers Title & Guaranty Co., 5M% Mtg. Par Ctfs. No. D 424421381 
Lawyers Title & Guaranty Co., Guaranteed 1st Mtg. Par Ctfs., 5%. 

No. 400572-16 

N. Y. Title & Mtg. Co., Guaranteed 1st Mtg. Ctfs.. 5M%. No. N97. . 
N. Y. Title & Mtg. Co., Guaranteed 1st Mtg. Ctfs., 4M%- No. N86. . 
Participating Ctf. in Consol. Bond and Mtg., SE. corner Madison 

Ave. and 40th St., Manhattan, 4% 



1944 
1940 
1935 

1942 
1938 
1940 



$98,482.13 
100,000.00 
80,000.00 

94,784.92 
90,000.00 
97,000.00 

90,000.00 



$650,743.36 



Total Mortgages. 



$650,267.05 



$22,674,743.36 



Bonds and Mortgages — Funds Invested . 



$22,528,292.25 



Number of 
shares 



120 

410 

500 

150 

300 
2,000 
1,125 
1,000 

225 

937.5 

400 

220 
1,000 

500 

400 

320 
5,000 



Preferred Stocks 

American Cyanamid Co., 5% cum. conv. pref., 1st ser. . . 
American Cyanamid Co., 5% cum. conv. pref., 2d ser.. . 

J. I. Case Threshing Machine Co., 7% cum. pref 

Central Illinois Light Co., 4M% cum. pref 

Cleveland Electric Illuminating Co., $4.50 cum. pref. . . . 

Consolidated Edison Co., $5.00 cum. pref 

E. I. Du Pont de Nemours & Co., $4.50 cum. pref 

General Motors Corp., $5.00 cum. pref 

Grant Co. (W.T.), 5% cum. pref 

Gulf, Mobile & Ohio R. R. Co., $5.00 pref 

International Nickel Co. of Canada, 7% cum. pref 

Johns-Manville Corp., 7 % cum. pref 

Northern States Power Co., $5.00 cum. pref 

Ohio Oil Co., 6% cum. pref 

Oklahoma Natural Gas Co., $5.50 cum. conv. prior pref. 

Sherwin-Williams Co., 5 % cum. pref 

U. S. Steel Corp., 7 % cum. pref 



$1,230.00 

4,766.25 

62,225.00 

17,025.00 

34,050.00 

198,725.00 

116,125.00 

124,875.00 

7,642.76 

8,085.94 

51,903.00 

27,897.20 

103,000.00 

52,661.10 

44,980.25 

35,436.80 

715,173.50 



14,607.5 



Total Preferred Stocks. 



$1,605,801.80 



Schedule of Securities — Continued 



Number of 
shares 



Description 



Cost, amortized 

cost, or 

value at date 

acquired 



2,600 
1,600 
1,400 
5,200 
5,500 

600 

900 

200 
1,500 
2,300 
1,600 
2,400 
2,000 
2,500 

100 
2,500 
1,608 
4,600 
3,500 
1,760 
2,200 
1,500 
35 
10,300 
1,700 
6,800 
2,900 

400 
1,875 
4,600 

700 
4,500 
3,500 

900 

820 
1,000 

783.30 
2,000 
3,700 
1,113 
3,400 
2,500 
1,100 
3,000 
4,100 
3,800 
2,000 
2,600 
2,500 
1,600 
1,900 
4,300 
1,200 
1,800 
1,100 
2,100 
2,500 
1,500 
8,000 
3,100 
1,858 
4,000 
2,200 

120 
3,600 
1,500 
1,200 

900 
2,600 



Common Stocks 

Air Reduction Co 

American Brake Shoe & Foundry Co 

American Can Co 

American Cyanamid Co. "B" 

American Radiator & Standard Sanitary Corp 

American Telephone & Telegraph Co 

American Tobacco Co 

American Tobacco Co. "B" 

Bethlehem Steel Corp 

Caterpillar Tractor Co 

Chase National Bank of New York 

Chrysler Corp 

Commercial Credit Co 

Commercial Investment Trust Corp 

Commercial National Bank and Trust Co. of New York 

Continental Can Co 

Continental Insurance Co 

Continental Oil Co 

Deere & Co 

Dow Chemical Co 

E. I. Du Pont de Nemours & Co 

Eastman Kodak Co 

First National Bank of New York 

General Electric Co 

General Foods Corp 

General Motors Corp 

Grant Co. (W. T.) 

Guaranty Trust Co. of New York 

Gulf, Mobile & Ohio R. R. Co 

Gulf Oil Corp 

Hartford Fire Insurance Co 

Hudson Bay Mining & Smelting Co., Ltd 

Humble Oil & Refining Co 

Ingersoll-Rand Co 

Inland Steel Co 

Insurance Co. of North America 

International Business Machines Corp 

International Harvester Co 

International Nickel Co. of Canada, Ltd 

Johns-Manville Corp 

Kennecott Copper Corp 

Kresge Co. (S. S.) 

Liggett & Myers Tobacco Co. "B" 

Monsanto Chemical Co 

Montgomery Ward & Co 

National Lead Co 

Newberry Co. (J. J.) 

New Jersey Zinc Co 

Owens-Illinois Glass Co 

Parke, Davis & Co 

Penney Co. (J. C.) 

Phelps Dodge Corp 

Pittsburgh Plate Glass Co 

Proctor & Gamble Co 

Pullman, Inc 

St. Joseph Lead Co 

Sears, Roebuck & Co 

Sherwin-Williams Co 

Socony Vacuum Oil Co 

Standard Oil Co. of California 

Standard Oil Co. of New Jersey 

Texas Corp 

Timken Roller Bearing Co 

Travelers Insurance Co 

Union Carbide & Carbon Corp 

United Fruit Co 

United States Gypsum Co 

United States Steel Corp 

Westinghouse Electric & Manufacturing Co 

Total Common Stocks 

Common and Preferred Stocks — Funds Invested. 

Aggregate Investments (Bonds and Stocks) 



$155 

74 
128 
149 
100 
100 

73 

16 
117 
162 

51 
226 

96 
147 

17 
110 

57 
132 

69 
211 
348 
238 

60 
407 

74 
360 

96 

104 

2 

174 

52 
148 
203 

96 

82 

64 
116 
164 
199 
106 
146 

55 
110 
304 
220 

87 

94 
172 
167 

72 
180 
160 
131 
100 

52 

95 
202 
147 

95 
109 

98 
169 
110 

59 
308 
109 
120 

92 
280 



863.00 
304.45 
250.00 
339.50 
533.00 
312.50 
424.50 
342.00 
325.00 
360.00 
800.00 
638.50 
345.00 
824.00 
880.00 
730.00 
185.30 
433.00 
662.50 
240.00 
983.50 
952.75 
925.00 
398.50 
426.50 
416.00 
781.24 
414.00 
812.50 
443.00 
184.68 
495.00 
590.50 
960.00 
930.00 
962.75 
998.00 
952.50 
217.00 
691.00 
532.50 
725.00 
625.00 
928.50 
701.08 
741.00 
190.00 
294.50 
995.00 
272.00 
210.00 
704.00 
399.75 
795.82 
645.00 
386.50 
234.40 
079.47 
645.00 
343.00 
627.38 
108.26 
436.00 
433.11 
145.50 
972.00 
301.00 
360.00 
194.50 



167,772.30 



$9,363 



351.94 



182,379.80 



$10,969 



$33,497 



Real Estate and Equipment, Original Cost 

Administration (October 31, 1940) 
Washington, D. C. 

Building, site, and equipment $842,956.88 

Division of Plant Biology (September 30, 1940) 
Stanford University, California (Headquarters) 

Buildings and grounds $77,467.56 

Laboratory 43 , 333 . 69 

Library 24,992.57 

Operating equipment 16,738.40 162,532.22 

Department of Embryology (September 30, 1940) 
Wolfe and Madison Streets, Baltimore, Maryland 

Library $3,802.07 

Laboratory 16,754.28 

Administration 7,540.47 28,096.82 

Department of Genetics (September 30, 1940) 
Cold Spring Harbor, Long Island, New York 

Buildings, grounds, field $288,749.45 

Operating equipment 32,516.03 

Laboratory apparatus 32 , 784 . 19 

Library 49 , 686 . 92 

Archives 45,488.90 449,225.49 

Geophysical Laboratory (September 30, 1940) 
2801 Upton Street, Washington, D. C. 

Building, library, operating appliances $230,174.75 

Laboratory apparatus 167 , 97 1 . 39 

Shop equipment 20,589.67 418,735.81 

Division of Historical Research (September 30, 1940) 
Administration Building, Washington, D. C. 

Operating equipment $30,717.27 

Library 9,769.44 40,486.71 

Nutrition Laboratory (September 30, 1940) 
29 Vila Street, Boston, Massachusetts 

Building, office, shop, and library $134 , 293 . 69 

Laboratory apparatus 37,261 .69 171,555.38 

Mount Wilson Observatory (September 30, 1940) 
Pasadena, California 

Buildings and grounds $222,458.33 

Shop equipment 46,715.80 

Instruments 680,715.60 

Furniture and operating appliances 143,805.08 

Hooker 100-inch reflector 633,896.41 1,727,591.22 

Department of Terrestrial Magnetism (September 30, 1940) 
5241 Broad Branch Road, Washington, D. C. 

Building, site, and office $235,680.13 

Survey equipment 96 , 899 . 75 

Instruments, laboratory, and shop equipment 391 ,435.05 724,014.93 



$4,565,195.46 



REPORT OF THE PRESIDENT 



OF THE 



CARNEGIE INSTITUTION OF WASHINGTON 



FOR THE YEAR ENDING OCTOBER 31, 1940 



REPORT OF THE PRESIDENT 

OF THE 

CARNEGIE INSTITUTION OF WASHINGTON 

In accordance with Article IV, section 2, of the By-Laws of the 
Carnegie Institution of Washington, the President has the honor to 
submit the following report on the operations of the Institution dur- 
ing the year ending October 31, 1940. 

The momentous events of the past year do not alter the position of 
the Institution, as traced in the last annual report; rather do they 
render its obligations more immediate and pressing. In the midst of 
intense national effort to provide adequate defense, it is imperative 
that the Institution respond promptly and effectively to every call 
from government, and that our facilities be made directly available 
whenever needed. On the other hand, with so much scientific effort 
already drawn into war activities in so many countries, the duty of 
carrying on and providing the continuity essential for best progress 
rests mainly on the few remaining scientists who can still continue 
in freedom to extend basic knowledge in a turbulent world. 

Fortunately the emergency has brought a quickened pace and a 
new intensity in scientific activities throughout this country, even in 
fields which are remote from the preparedness program. When a 
nation is in danger, and this danger becomes fully appreciated by its 
people, slumbering loyalties are aroused, petty disagreements dis- 
appear, and simple patriotism regains its rightful place. A democracy 
may exhibit a confusing dissidence in times of peace, but the very 
freedom of expression which produces discord as each small group 
pursues its limited objectives acts powerfully to unite and stimulate 
when common self-interest becomes focused by a single clear threat. 
Mass thinking takes time to crystallize, and is accompanied always 
by disturbing impurities and contaminations, but the strength of the 
resulting product is very great. 

3 



CARNEGIE INSTITUTION OF WASHINGTON 

Science feels this influence early. The urge to do something for 
humanity, by improving its knowledge of its environment, is so 
allied to the urge to do something definite to protect one's country 
from aggression that all scientific effort responds to the stimulus. 
This is one of the reasons why fundamental scientific advance, and 
in fact basic intellectual accomplishment of many kinds, is often 
accelerated rather than retarded by national stress. This is illustrated, 
for example, by the magnificent achievements of the coterie of 
thinkers who appeared in France during the terrible years follow- 
ing the Revolution. Freedom combined with danger brings out 
some of the finest attributes of the race. The sad part of it is that 
the danger needs to be clear and immediate in order to be fully 
operative; and when danger is pressing it may be succeeded by waste 
and the destruction of moral as well as physical values. 

This powerful stimulant has already begun to flow through the 
veins of the Institution. A quickened tempo is excellent, but we must 
not let it tempt us to hasty work or conclusions on insufficient evi- 
dence. Those scientists whose best work can be accomplished in 
fields far removed from defense activities should not permit the 
pressure of the moment to dim the vista of slowly evolving knowl- 
edge toward which they advance. The need for more thorough 
scientific knowledge on which a better civilization can be securely 
based is not lessened by the hazards that confront it. 

For the scientist whose talents apply directly to the means by 
which a nation defends itself, the way is glaringly clear. He needs 
to remember that there are many who labor on the unspectacular for 
every one who manipulates the vital controls, and that the inevitable 
confusion which accompanies a change in the whole mode of life of 
a nation necessarily wastes fine capabilities on minor things. He 
should realize that anonymity and isolation replace the public appre- 
ciation and the open scientific fellowship to which he is accustomed. 
He may well regret deeply that his efforts, so long devoted to an 
altruistic ideal embracing the whole of mankind, become limited for 
a time to a narrower national aim. But he shares in that primal joy 

4 



REPORT OF THE PRESIDENT, 1940 

that comes from intense group effort in defense of his home, subli- 
mated it is true, but just as real as though he stood at the mouth of 
a cave with a few strong men of the clan armed with stone axes 
against a hostile world. 

Finances 

The income from endowment continues to decrease. The Finance 
Committee and the Investment Office are faced with an especially 
grave responsibility in this Institution, where the presence of large 
continuing obligations renders essential a substantial continuing in- 
come. A balance is being maintained between that policy of invest- 
ment which would impose undue risks upon the future capital posi- 
tion for the sake of large immediate return, and that abrupt curtail- 
ment of income, in order to insure capital, which would jeopardize 
the health of a going concern. Thus far it has been possible to con- 
tinue all our major efforts without embarrassment, and in fact with 
sound growth in many areas. 

However, the current situation has been transformed during the 
year by the action of Carnegie Corporation of New York in making 
to the Institution an emergency grant of $750,000, payable at the rate 
of $150,000 annually for five years. This generosity is keenly appre- 
ciated, especially as it comes at a time when the income of the 
Corporation is sharply curtailed, so that internal readjustment of 
Corporation plans was necessary in order to make the grant to the 
Institution possible. 

This grant restores the Institution to the sound condition in which 
a substantial portion of its available funds may be directed toward 
temporary efforts by its own staff and by others with which it coop- 
erates. Taken together with Institution funds already devoted to 
such efforts, it makes approximately 15 per cent of the total income 
available for these purposes. This provides a flexibility which it is 
highly important to maintain. The emphasis of science shifts with 
advancing knowledge, and it is essential that the Institution be 
enabled to redirect its attack accordingly. The Carnegie Institution 

5 



CARNEGIE INSTITUTION OF WASHINGTON 

of Washington is more than merely an additional independent re- 
search organization in American science. By reason of its scientific 
scope and its geographic spread the influence of the Institution per- 
meates the entire fabric of the scientific effort of the country in a 
stimulating and helpful manner. In order that it may fully meet 
its obligations in this regard, a reasonable amount of flexibility is 
imperative, and this has now been attained. 

For this reason recent budgets have been prepared with the inten- 
tion of maintaining the balance between long-range obligations and 
terminating projects. Hence, although the fine accomplishments of 
many departments indicate ways in which the continuous efforts 
could be usefully expanded, these opportunities have been gen- 
erally postponed in favor of temporary projects and grants to coop- 
erating groups. It is, of course, essential that the Corporation grant 
be applied only to terminating projects, for the grant itself terminates 
in five years. The need for maintaining fluidity demands such a 
course and its further extension to that portion of the Institution's 
income not required to meet continuing obligations of regular 
operation. 

The year 1939 closed with a substantial excess of income over 
estimates. The present year promises to terminate with close agree- 
ment between these two items, so that most if not all of the unap- 
propriated income from 1939 will remain available. By utilizing this 
carry-over in 1941, and on the basis of income as now estimated, a 
budget is presented which is balanced without calling on reserves, 
and provides a sufficient amount in the General Contingent Fund 
for the extra expenses and readjustments which are normally ex- 
pected. If income continues to decrease, we shall soon be faced with 
the alternative of drawing on reserves, of curtailing regular opera- 
tions, or of sacrificing the desirable flexibility so recently acquired. 
It is not possible to see far ahead on such matters, and fortunately a 
decision does not need to be made at this time. Next year it may be 
necessary to choose. Since we are certainly going through an emer- 
gency period, and since we have in the past accumulated an emer- 

6 



REPORT OF THE PRESIDENT, 1940 

gency reserve fund for just such purposes, it may later be wise to 
draw temporarily on this fund if necessary, in the hope that the 
emergency may pass. 

Plant and Facilities 

A number of changes in our physical plant have occurred during 
the year. 

The small property at Carmel, California, used by the Division of 
Plant Biology, has been sold. The active program at that locality 
terminated some time ago, but a portion of the property has since 
been used by individuals in post-retirement study. As such study 
could be conducted elsewhere, and as maintenance and depreciation 
were a burden, it became evident that the property should be sold. 

In pursuance of the program reported last year, the activities of 
the Marine Biological Laboratory at the Dry Tortugas have been 
terminated. Much of the equipment has been transferred to other 
laboratories of the Institution. One fairly large boat remained. This 
has now been presented to the Woods Hole Oceanographic Institu- 
tion, where it will continue to be fully useful in scientific research. 

In terminating our effort at the Desert Laboratory, at Tucson, 
Arizona, we have succeeded in avoiding the sacrifice of valuable 
elements. The work of Dr. Shreve will continue under our auspices. 
Much of the program which the Institution there initiated many 
years ago has become incorporated into the large operations of the 
government in connection with forestry, soil conservation, and the 
public domain. We have therefore transferred the property at 
Tucson to the Forest Service for use in its research program, which 
has objectives closely parallel to those which prompted the early 
establishment of this laboratory. In this connection they plan to 
maintain the isolated area which has been preserved by the Institu- 
tion for many years. 

The principal addition to plant, reported upon last year, is the 
cyclotron under construction at the Department of Terrestrial Mag- 
netism with aid of funds from the Carnegie Corporation of New 

7 



CARNEGIE INSTITUTION OF WASHINGTON 

York. This particular department, by reason of its nature and loca- 
tion, is already considerably burdened by its efforts for the national 
government. The construction program, however, is not seriously 
delayed as yet, and it is still planned to put the cyclotron into opera- 
tion early next year. 

We continue to cooperate closely with the California Institute of 
Technology in the construction of the great 200-inch telescope. It 
would not be unexpected if delay in this program were forced by 
the present emergency. In any case the figuring of the mirror is a 
time-consuming affair, and completion cannot well be expected in 
less than eighteen months. 

With approval of the Executive Committee, accommodations have 
been provided in the Administration Building of the Institution for 
headquarters and offices of the National Defense Research Com- 
mittee, of which the President is Chairman. In addition a contract 
has already been effected with this Committee, and others are in 
contemplation, whereby facilities of the Institution, including per- 
sonnel and equipment, are being made available for study of defense 
research problems. 

Retirements 

The science of embryology was enormously furthered when the 
insight of Dr. Mall led to the establishment of the Department of 
Embryology at Baltimore. He was succeeded by Dr. George L. 
Streeter, who, after a service of 26 years, during 21 of which he 
served as Director, has now retired, beloved and admired by all his 
scientific colleagues. On the invitation of Johns Hopkins Uni- 
versity, and with support from Carnegie Corporation of New York, 
Dr. Streeter will continue with his personal researches there. He 
has been succeeded in the directorship by Dr. George W. Corner, 
who comes to us from the University of Rochester. We can look 
forward to a further period of high accomplishment under his 
leadership. 

The Assistant Director of Mount Wilson Observatory, Dr. Fred- 



REPORT OF THE PRESIDENT, 1940 

erick H. Seares, also retired from active service during the year. We 
have, in recent years, called upon Dr. Seares for much administra- 
tive effort in the affairs of the Observatory, and he has hence been 
unable to complete before retirement certain important personal 
research programs. For this reason he has been extended moderate 
post-retirement support to enable him to finish this work. 

Dr. Warren H. Lewis retired from the Department of Embryology 
after a distinguished career, marked by notable advances which 
brought to him, and thus to the Institution, wide recognition. He has 
accepted an invitation from the Wistar Institute at Philadelphia to 
join them in the furtherance of their biological program. 

Review 

The Year Book as a whole presents the review of the efforts of 
the Institution for the year. All that the report of the President can 
do is to direct attention and to emphasize. There is a certain inepti- 
tude in this procedure, for it does not follow that those results which 
are most readily summarized in a few simple words are the ones 
which primarily warrant the attention of the Trustees. Fortunately 
the reports of the various Directors meet this situation to a consider- 
able extent, for they are largely devoted to summarizing progress 
in the various fields. The President might therefore restrict this 
section of his report to the suggestion that these various summaries 
be consulted. Yet, if it is understood that selecting out certain matters 
for comment does not imply any listing in order of inherent impor- 
tance, it is well to direct attention to a number of subjects of special 
significance and interest, and to comment on their relation to our 
program as a whole, and on the general objectives before us. 

Terrestrial Sciences 

There is no word which groups into a single science the physics 
and chemistry of the materials of which the earth is constructed. 
The terrestrial sciences are today much subdivided, and the broad 
term geology no longer embraces them all. Without an understand- 

9 



CARNEGIE INSTITUTION OF WASHINGTON 

ing of the way in which this science has grown, the names of our two 
departments operating in this field might well be misleading. The 
Geophysical Laboratory deals with the chemistry as well as the 
physics of the rocks. The Department of Terrestrial Magnetism is 
as much interested in electric as in magnetic effects, in the body of 
the earth as well as the atmosphere and ionosphere. The interests 
of these two departments necessarily overlap. Some day, if termi- 
nology could be thereby clarified, we might consider renaming these 
two groups. Even if we did so, however, the changing trends of 
scientific interest might soon render the new names inaccurate, unless 
we were to pursue the unwise procedure of restricting the activities 
of a group strictly to the scope of its name. This would certainly 
be unfortunate in these days when groups as far apart in interest as 
geneticists and physiologists on the one hand, and students of ter- 
restrial science on the other, utilize the same great instrumentalities 
such as the new cyclotron. 

Both laboratories of the terrestrial sciences have a keen interest 
in the properties of materials under enormous pressures. They have 
cooperated during the year on a program which substantially extends 
the limit of experimentation in this regard. The device which makes 
this possible is a cascaded pressure equipment. This is much more 
than merely one pressure stage inside another, with each contributing 
its normal amount to the total pressure produced. The internal stage 
contributes much more than it could acting alone, for its very pres- 
ence in a region of high hydrostatic pressure gives it an abnormal 
strength. It is an ingenious new concept, and Goranson has care- 
fully developed the theory which explains it. We have already 
reached pressures of 200,000 atmospheres, that is, three million 
pounds per square inch, and physical measurements of certain kinds 
can be conducted with material under this pressure. We hope, of 
course, to learn more in this way of how materials behave deep down 
in the earth. 

Some of the processes by which the earth was molded still con- 
tinue before our eyes. In volcanoes we can observe violent phe- 

10 



REPORT OF THE PRESIDENT, 1940 

nomena of this sort in action, as our research associate, Perret, has 
done for many years all over the world. He is now gathering and 
correlating his findings for publication. We can also make measure- 
ments, and our recent expedition to Guatemala tried out some of 
the methods used in geophysical prospecting as a means of ascer- 
taining subterranean conditions near an active volcano. Finally, in 
the laboratory, some of the phenomena can be precisely examined 
on a small scale. One such experiment this year produced a molten 
rock which, when quenched, frothed into a light pumice. The way 
in which this takes place is not yet clearly understood, and a full 
grasp of the matter may well throw a revealing light upon the 
processes of volcanism. 

The science of meteorology has made great strides in recent years, 
owing to the adoption of new and powerful analytical methods and 
the keen interest in the subject in connection with aeronautics. The 
Institution has no large program in the applied aspects of meteorol- 
ogy, but many of the investigations of the Department of Terrestrial 
Magnetism impinge upon it. A full knowledge of the atmosphere 
is fundamental to the subject, and our studies of the electrical con- 
ditions of the upper layers are of importance in this connection. The 
use of radio echoes continues to yield important data; and Ellis 
Johnson has under way as well a considerable program, involving 
the use of a flickering searchlight, by which the electrical and chem- 
ical conditions of the air at great heights may be examined. 

Astronomy 

As we ascend from the earth, the atmosphere becomes thinner 
until at a distance of a few hundred miles there is almost nothing. 
Within the solar system are occasional grains of sand, and the 
pebbles which sometimes flare briefly as meteors when they strike 
the atmosphere. Out in space beyond the solar system are dark 
clouds of dust which obscure the stars, and pose serious problems 
for the astronomer. These are receiving careful attention from Seares 
in order that their effects may be properly allowed for. In the vast 



CARNEGIE INSTITUTION OF WASHINGTON 

regions beyond the galaxy, in interstellar space, there is very little. 
But not quite absolutely nothing, for there is a faint sky light which 
comes to us from a few far-wandering molecules. The nature of 
these was predicted by McKellar, of the Dominion Astrophysical 
Observatory, and Adams at Mount Wilson has now confirmed by 
measurement that at least two organic gases are there present. The 
power of the spectroscope was never more strikingly demonstrated 
than by this identification of an organic gas, located at enormous 
distances from the earth, and so attenuated that it constitutes the 
least concentration of matter that man has ever studied. Yet there 
is much space between the stars, and the total amount of matter 
present in this form may well be a significant element in cosmology. 
The science of astronomy is often considered a thing apart from 
the everyday affairs of this earth, which draws upon the physical 
sciences for its instrumentation and yields in return only an aid in 
the development of the physical sciences themselves, in the form of 
a remote laboratory where strange and extreme physical phenomena 
can be watched, even if they cannot be controlled. Yet, within the 
scope of the work of this Institution there are at least three direct 
interlinkages between astronomy and our other disciplines, by reason 
of radiations coming to the earth from outer space. The sun is our 
most important star, and its light furnishes the energy for all our 
affairs. It enables photosynthesis to proceed, that plants may grow, 
and animals may be thereby nourished. To this we shall return 
presently. There are also electrified particles proceeding from the 
sun, and these affect the condition of our upper atmosphere, so 
that sunspots and magnetic storms upon the earth are interrelated. 
Finally, there are cosmic rays falling upon the earth in a continual 
shower, so that every individual is penetrated through and through 
during his lifetime by projectiles that disrupt atoms all along their 
path, sometimes by direct hits which shatter them into small bits. 
Fortunately these projectiles, as well as those coming from radio- 
active material of the earth, are not highly concentrated. They may, 
however, be significant in the process of evolution. 

72 



REPORT OF THE PRESIDENT, 1940 

Biological Sciences 

At the Department of Genetics there is being investigated, as at 
other places, the mechanism by which these rays, as well as others 
such as X-rays and streams of neutrons, cause mutations and hence 
the appearance of individuals differing in abrupt manner from their 
ancestors. The study of the ways in which the chromosomes may be 
split into pieces, and yet rejoin, often in a new arrangement, so that 
reproduction may proceed, is one of the most fascinating pursuits of 
all science. It has just been found that a very considerable delay may 
occur between the fracture and the rearrangement. There are other 
ways of modifying the process experimentally for study, for example 
by the use of alkaloids to cause the doubling of chromosomes, and 
this, under the skillful manipulation of Blakeslee, has produced 
much new knowledge. The evolution of the individual, as well as 
the evolution of species, undoubtedly depends upon the genes in the 
chromosomes, but it is affected as well by other influences. In the 
individual there is a subtle effect of the environment modifying the 
direct hereditary process in such a matter as the transmission of sus- 
ceptibility to disease, as has been found by MacDowell in his studies 
of leukemia in mice. There is also involved a complex relationship 
with the endocrine system, furnishing perhaps a mechanism by which 
the genetic constitution of an individual affects its development, but 
also perhaps reacting to complicate the genetic process itself. The 
endocrine secretions, with their powerful influence upon the indi- 
vidual and their strange interrelations, furnish an involved field of 
study because of the difficulty in strictly isolating individual effects 
for study. The pigeon, as handled by Riddle, with advanced experi- 
mental technique, has proved to be a very useful laboratory object. 

The understanding of the evolution of species has proceeded far 
since the concepts of Darwin and his immediate successors. The 
interaction between an altering environment and a race of varied 
genetic constitution does not necessarily result in the appearance of 
new species. Mutations undoubtedly play a part, but their exact place 

13 



CARNEGIE INSTITUTION OF WASHINGTON 

in the process is not yet entirely clear. Much light is now being 
thrown upon this whole complex matter. The study of the genetic 
constitution of natural populations of Drosophila by Dobzhansky has 
yielded some unexpected data. At the Division of Plant Biology 
Clausen, Hiesey, and Keck have summarized in a volume their 
long-continued transplant experiments, through which some of the 
mechanisms of evolution which are now in operation among plants 
of the Pacific slopes are traced back to definite causes. This study, 
combining a careful evaluation of the genetic situation with a con- 
trolled variation of the environment, promises to be of great signifi- 
cance. Clements is rounding out his own study of the matter and 
promises a comprehensive summary of his opinions and findings. 

In the Division of Plant Biology there is also in progress the highly 
interesting study of several aspects of photosynthesis. Spoehr is using 
a new method which, though not yet fully developed, promises 
much. If a seed be grown in the dark, its progress halts as soon as 
it has used up all its initial food supply, for in the absence of light 
it cannot manufacture more. It can be artificially fed, however, and 
it will then proceed. When certain simple substances are injected it 
cannot develop far, and others must then be supplied. The materials 
that must be artificially supplied are clearly those for which photo- 
synthesis is necessary, while those which can be omitted are second- 
ary products. The study is not simple, for the process of chemical 
manufacture in the plant is intricate, so that much work will be 
necessary before definite conclusions can be drawn. The key may not 
unlock all the doors, but, in combination with other powerful meth- 
ods such as the continuing use of radioactive tracers, it should open a 
further region in the field of the photosynthetic processes of nature. 

Study of the evolution of the individual begins with the science of 
embryology. The mystery which has always surrounded the way 
in which an apparently simple egg develops into a complex being, 
with all the consequent fine balancing of physiological processes, still 
remains. A single cell, sometimes too small to be seen by the naked 
eye, with microscopic chromosomes, and genes beyond the power 

14 



REPORT OF THE PRESIDENT, 1940 

of any optical device, proceeds to subdivide, and soon the resultant 
cells take on new individuality in accordance with their ultimate 
destiny in the final structure. Nerve cells interthread the embryo 
and establish controls. Chemical messengers, the hormones, are 
manufactured to regulate the joint functioning of distant parts. 
Bones are deposited to furnish support, channels are built to conduct 
the fluids by which chemicals are transported. An eye is built; an 
ear is formed. Finally there emerges a complete being, finely ad- 
justed to carry on a varied existence, and to reproduce itself in turn. 
The design for all this process was somehow present in the minute 
egg. With all our science we are still incapable of true understand- 
ing of this profound fact. Yet we can trace, record, experiment, and 
study; and the knowledge grows piece by piece. It is no wonder 
that embryology leans heavily on its neighboring sciences, and that 
embryologists strive to reduce their findings more and more to a 
secure quantitative basis. One occasionally finds a physicist who feels 
that he now knows much, but one never finds an embryologist who 
is not humble in the presence of his great problem. 

Historical Research 

Evolution has many aspects, a principal one of which still remains 
to be mentioned in closing this report of the Institution's activities. 
The historian studies the evolution of races in recorded time, and 
the archaeologist in the time before man inscribed the accounts of 
his diverse affairs. Kidder has well presented the importance of such 
researches in these days when the future of all scientific effort is 
affected by the faulty relations between nations and the power of the 
instruments of destruction which man has created. The history of 
man covers but a brief moment in the entire time of a long evolu- 
tion, but it is a feverish moment in which events occur with startling 
rapidity. What we are now experiencing is not the first effort of a 
civilization to acquire a balance for continuing progress, and we are 
yet to learn much as we continue to unravel the threads of other 
civilizations which have developed, culminated, and disappeared. 

15 



CARNEGIE INSTITUTION OF WASHINGTON 

William Benson Storey 

William Benson Storey died in Chicago on October 24, 1940, at 
the age of eighty-three, after an outstanding career in engineering 
practice and administration. He was elected a member of the Board 
of Trustees of the Institution on December 12, 1924, and served as a 
member of the Auditing Committee from 1928 to 1939. He always 
showed continued and helpful interest in the welfare and progress 
of the Institution and its activities. Only infrequent illness prevented 
him from attending and actively participating in the affairs of the 
Board. 

By reason of his high ideals, integrity, and wealth of experience, 
Mr. Storey contributed much toward maintaining and improving the 
position occupied by the Institution in the world of American science. 

Vannevar Bush, President 



16 



REPORTS OF DEPARTMENTAL ACTIVITIES 
AND COOPERATIVE STUDIES 

ASTRONOMY 

Mount Wilson Observatory 
Special Projects 

TERRESTRIAL SCIENCES 

Geophysical Laboratory 

Department of Terrestrial Magnetism 

Special Projects 

BIOLOGICAL SCIENCES 

Division of Plant Biology 

Department of Embryology 

Department of Genetics 

Nutrition Laboratory 

Special Projects 

HISTORICAL RESEARCH 

Division of Historical Research 
Special Projects 



MOUNT WILSON OBSERVATORY 

Pasadena, California 

WALTER S. ADAMS, Director 
FREDERICK H. SEARES, Assistant Director 



The work of an active year at the Observa- 
tory has been aided to an unusual extent by 
the addition of new instruments and the 
improvement of existing equipment. The re- 
modeling of the 6o-foot tower telescope has 
provided a modern instrument of greatly im- 
proved optical quality and high efficiency for 
continuous records of the sun's surface and 
detailed studies of the phenomena of its 
atmosphere. In cooperation with the National 
Geographic Society the Observatory has de- 
signed and helped to construct a special type 
of telescope and much spectrographic equip- 
ment, primarily for the observation of 
eclipses, but available also for other types of 
solar investigation. Two stellar spectrographs 
of unusual design and high light-efficiency 
have been completed for the study of very 
faint light-sources such as supernovae, extra- 
galactic nebulae, and stars of very low in- 
trinsic luminosity. The rotation of extra- 
galactic nebulae is one of the chief problems 
now under investigation with these instru- 
ments. The use of more transparent glasses, 
of cameras of special design, and of thin 
fluoride films to reduce losses by reflection at 
the optical surfaces has brought within the 
range of observation objects quite out of reach 
some years ago. 

The maximum of sunspot activity passed 
nearly two years ago, but, as frequently hap- 
pens in solar cycles, the maximum was of the 
"broad" type, with large numbers of spots 
appearing at intervals over a period of several 
years. As a result spots have been numerous 
during the past year and studies of their 
spectra, especially in the ultraviolet region, 
and of their magnetic fields have been impor- 
tant features of the solar work. About 96 per 
cent of the spots observed have signs of the 
magnetic field in agreement with Hale's law 
governing the signs in the two solar hemi- 
spheres. Certain weak magnetic fields dis- 



covered in the vicinity of spots have been 
found to have signs opposite to those of the 
spots themselves, and studies of the vortex 
structure often surrounding spots provide 
further evidence that the whirls are probably 
hydrodynamical in origin. The development 
of a new interference method for measuring 
weak magnetic fields should be of great value 
both for investigations of small spots and for 
the solution of the difficult problem of the 
sun's general magnetic field. 

The important question of the intensities of 
the dark lines in the solar spectrum has been 
investigated with a photoelectric mono- 
chromator. This instrument measures the 
energy directly, thus eliminating many of the 
difficulties of the photographic process; and 
through refinements of the apparatus, meas- 
urements have been extended even to some 
of the fainter details of the spectrum. The 
quantity of energy emitted in the spaces be- 
tween the lines indicates that the sun differs 
greatly from a black body in its radiation. 

Our knowledge of the materials constitut- 
ing the visible surface of the moon has been 
notably increased during recent years, mainly 
through the work of Wright, of the Geo- 
physical Laboratory. During his visits to 
Mount Wilson he has skillfully applied several 
methods of approach to this problem, espe- 
cially through measures of the polarization 
of the reflected light. Recent observations of a 
total lunar eclipse agree in indicating that the 
drop in temperature as the earth's shadow 
passes across the moon's disk is such as would 
be expected from a surface covered with a 
thin layer of fine dust or ash. During totality 
the temperature dropped from 370 ° C abso- 
lute to 1 75 . 

Planetary observations have been limited to 
determinations of position of the fainter satel- 
lites of Jupiter, including the two discovered 
by Nicholson about two years ago, and to 



CARNEGIE INSTITUTION OF WASHINGTON 



some spectroscopic observations of Mars. The 
amount of water vapor above the equatorial 
areas of Mars is found to be definitely less 
than 5 per cent of that in the earth's 
atmosphere. 

Of the many stellar investigations of the 
year, several have dealt with the brightness, 
colors, motions, and luminosities of special 
groups of stars. Accurate measures of bright- 
ness are fundamental to all stellar astronomy, 
and the completion of a catalogue giving the 
magnitudes and colors of 2271 stars north of 
declination +8o° forms a most valuable con- 
tribution to this field. An extension of the 
sequence of standards of reference to stars as 
faint as magnitude 20.5 has been found neces- 
sary for investigations of nebulae and faint 
star clouds. 

Direct measurements of distance have 
added several stars to those known to be 
among the nearest neighbors of the sun. Two 
of these give out less than one ten thousandth 
part of the sun's light. Closely related to 
these trigonometric measures of distance are 
those of the motions of stars across the sky, 
their proper motions, which provide average 
distances and luminosities for classes of stars 
too distant to be measured directly. Data of 
this sort, combined with motions in the line 
of sight, have furnished a new determination 
of the period of rotation of our galaxy, and 
of the absorption of light by obscuring clouds 
in space as a function of distance from the 
sun. 

A direct and valuable measure of space 
absorption of light is also provided by accu- 
rate measurements of the colors of more than 
1300 stars, mainly in the neighborhood of the 
Milky Way. The greater the amount of 
cosmic dust, the greater is the reddening of 
the transmitted starlight, and thus the forms 
of the great irregular obscuring clouds can to 
a considerable extent be charted and defined. 
Similar observational material is also serving 
to determine the ratio of the total absorption 
of light by the cosmic clouds to the absorption 
in different colors. 

Studies of stellar spectra have dealt in part 
with the motions of stars as determined from 



displacements of the spectral lines, and in part 
with their physical characteristics. In the first 
class are the measures of radial velocity of 
several hundred stars in the Selected Areas 
of Kapteyn and other special regions, studies 
of spectroscopic binaries and other stars show- 
ing variable radial velocity, and such an in- 
vestigation as the determination of the solar 
parallax from the radial motion of Arcturus. 
To the second class belong the observations of 
the spectra of several varieties of variable 
stars, especially the nova-like stars of the SS 
Cygni type, discoveries and identifications of 
molecular bands in the spectra of the cooler 
stars, studies of stars showing emission lines 
in their spectra, and an extensive investigation 
of the remarkable eclipsing star t, Aurigae. 
Some of the specific results are the discovery 
of the first known spectroscopic binary of the 
early Wolf-Rayet type of spectrum; the identi- 
fication for the first time of molecular bands 
of SiN, of the carbon isotope in C 13 N 14: , and 
of Ca 2 in stellar spectra; the discovery of 
several double absorption lines in the spec- 
trum of Ceti; and a determination of the 
excitation temperature and other physical con- 
ditions at a number of levels in the atmos- 
phere of X, Aurigae. 

The interesting problem of the composition 
of the gases in interstellar space has been 
studied from several points of view. Marked 
differences have been found in the distribu- 
tion of calcium and sodium gases in different 
regions of space, and also in the relative 
abundance of calcium and other gases which 
are now beginning to be identified. The dis- 
covery of a faint interstellar line in the 
spectrum of the relatively near star a Virginis 
affords a means for calculating the density 
of the ionized calcium gas in the general 
region of space near our sun. This proves to 
be of the order of 3 X io" 10 ions per cubic 
centimeter, but it is clear that the density is 
not uniform throughout the galaxy. 

Definite evidence of the presence of com- 
pounds in interstellar space has resulted from 
the Mount Wilson observations combined 
with the theoretical studies of McKellar of 
the Dominion Astrophysical Observatory and 



MOUNT WILSON OBSERVATORY 



others. All the important predicted lines of 
the hydrocarbon gas CH have been observed, 
and the evidence for cyanogen CN is nearly 
as conclusive. It is highly probable that the 
two or three remaining unidentified sharp 
lines which are fairly prominent will also be 
found to be due to the molecules of familiar 
gases. At present the recognized elements in 
interstellar gases are neutral and ionized 
calcium, neutral sodium, neutral potassium, 
ionized titanium, all in the atomic form, and 
molecular CH and CN. 

Two nebulae within our galaxy have been 
investigated for expanding motion and the 
distance of one of these, the well-known fila- 
mentary nebula in Cygnus, has been found to 
be less than iooo light-years. Some interest- 
ing photographs of galactic nebulae showing 
unusual detail have been made with red- 
sensitive plates and Kodachrome films. 

In the wide field of study of the extra- 
galactic nebulae, emphasis has gradually been 
shifting from general surveys to specific prob- 
lems. This has been particularly true in 
nebular spectroscopy, where gains in instru- 
mental light-efficiency have made it possible 
to use higher dispersion than heretofore on 
important individual nebulae. One valuable 
result is the establishment with higher accu- 
racy of an extreme point on the velocity- 
distance curve, a nebula in Bootes showing a 
red shift corresponding to a radial velocity 
of +39,000 km/sec. The rotation of one 
nebula has been studied in detail with the 
spectrograph, and from among the iooo 
brightest nebulae in the northern sky three 
others have been selected for observation 
which should yield an answer to the interest- 
ing question of the direction of rotation. A 
program is also being devised for more accu- 
rate determinations of the radial velocities of 
the components of double nebulae, data 
which would yield values of nebular masses. 
Existing results suggest an upper limit of 
mass of the order of io 10 suns. 

The classification of 800 nebulae brighter 
than the 13th magnitude has been completed, 
and the results are now being analyzed. Iso- 
lated nebulae are comparatively rare, compris- 
ing 5 per cent of the elliptical nebulae and 
15 per cent of the late-type spirals. Two 



dwarf nebulae of low luminosity have been 
discovered, characterized by low surface 
brightness and small color index. These fea- 
tures may prove to be criteria for the dis- 
covery of such systems. 

A study by Randers of the structural form 
of nebulae from a hydrodynamical point of 
view indicates that the ejection of matter 
from rotating lenticular nebulae is not ade- 
quate to produce the observed evolutionary 
forms. The importance of ring formations 
arising from viscosity in a differentially rotat- 
ing system is emphasized as an agency in the 
process of development. 

A quantitative investigation by Holmberg 
of the clustering tendency of nebulae leads to 
interesting results from the point of view of 
the capture theory. Using as reliable values 
as possible for nebular masses, space velocities, 
and capture distances, he concludes that a 
distribution similar to that observed would 
occur in a stationary universe with random 
distribution of nebulae in a period of 2 X io 12 
years. In a rapidly expanding universe such 
a distribution would be unlikely to occur 
unless the expansion were very irregular in 
nature. 

Three supernovae in extragalactic nebulae 
discovered during the year at Palomar have 
been observed spectroscopically and their 
light-curves determined at Mount Wilson. 
The spectra of the last two represent a new 
type, differing radically from the spectrum of 
any supernova observed previously. For a 
few days after maximum of light the spec- 
trum is continuous, with high intensity in the 
blue region; the continuous spectrum then 
begins to fade and broad bright bands develop 
with widths corresponding to velocities of 
5000 km/sec or more on the assumption of 
expanding shells. Although complete identi- 
fication is difficult, the main bands including 
those due to hydrogen can readily be recog- 
nized. In general the spectrum resembles that 
of ordinary galactic novae, but the tempera- 
ture is considerably higher, of the order of 
40,000° C. 

The work of the physical laboratory has 
included an extensive investigation with the 
electric furnace of the spectrum of the rare 



CARNEGIE INSTITUTION OF WASHINGTON 



earth gadolinium, which has been utilized by 
Russell and Albertson in a term analysis of its 
exceedingly complex structure. Special atten- 
tion has also been given to investigations 
which will aid in the interpretation of solar 
and stellar spectra, and studies have been 
made of titanium oxide and carbon bands, 
including those of the isotope C 13 , and of the 
rare element scandium. Of especial application 
to the results of the photometry of the lines 
of stellar spectra have been the measurements 
of the so-called "/-values," statistical factors 
entering into the intensities of individual 
lines; and investigations of accurate photo- 
metric methods of deriving the intensities of 
emission lines. 

A special study of the extreme ultraviolet 
absorption spectra of hydrogen and rare gases 
has been made by Takamine and Tanaka in 
the physical laboratory. Eight of the lines of 
hydrogen, most of the resonance lines of neon, 
and the resonance line of helium at A584 were 



observed in absorption and their structure has 
been thoroughly investigated. 

At the close of this brief account of the 
activities of the past year, the Observatory 
wishes to record its deep appreciation of the 
many services of Dr. Frederick H. Seares, 
who retired as a member of the staff on 
June 1. Dr. Seares has been associated with 
the Observatory for thirty-one years, and has 
served during much of that period as Assist- 
ant Director and Editor of the Observatory 
Publications. His appointment as Research 
Associate will enable him to continue his 
photometric investigations. 

The death on March 20 of Ferdinand Eller- 
man removed one of the members of the 
small group associated with the Observatory 
from its foundation in 1904. Although he 
retired from active service in 1937, he re- 
tained a profound interest in the Observatory, 
and his loss is felt most deeply by his associ- 
ates of many years. 



STAFF AND ORGANIZATION 



Research Division 

Solar Physics: Seth B. Nicholson, Harold D. 
Babcock, Joseph Hickox, Edison Hoge, 
Edison Pettit, Robert S. Richardson, Mary 
F. Coffeen, Elizabeth S. Mulders, Myrtle L. 
Richmond, Louise Ware. 

Stellar Spectroscopy: Walter S. Adams, Wil- 
liam H. Christie, Theodore Dunham, Jr., 
Milton L. Humason, Alfred H. Joy, Paul 
W. Merrill, Rudolph Minkowski, Roscoe F. 
Sanford, Gustaf Stromberg, Olin C. Wil- 
son, Ada M. Brayton, Cora G. Burwell, 
Dorothy J. Carlson, Alice L. Lowen. 

Stellar Photometry: Frederick H. Seares, 
Walter Baade, Mary C. Joyner. 

Nebular Photography and Spectroscopy: Ed- 
win Hubble, Walter Baade, Rudolph Min- 
kowski, Milton L. Humason, Dorothy J. 
Carlson. 

Trigonometric Parallaxes and Proper Mo- 
tions: Adriaan van Maanen, Ralph E. 
Wilson, Alice L. Lowen. 

Physical Laboratory: Arthur S. King, John 
A. Anderson, Robert B. King, Edward F. 
Adams, Ada M. Brayton. 



Editorial Division: Frederick H. Seares, Paul 
W. Merrill, Elizabeth Connor, librarian, 
Alice S. Beach, secretary and stenographer. 

Research Associates 

Sir James Jeans, Dorking, England; Henry 
Norris Russell, Princeton University; Fred- 
erick H. Seares, Pasadena; Joel Stebbins, 
University of Wisconsin. 

Temporary Associates 

Numerous visiting scientists, in addition to 
the research associates, spent periods of one 
to several months at the Observatory engaged 
in special investigations. Among these, Dr. 
Walter Albertson, of the Massachusetts Insti- 
tute of Technology, worked on the analysis 
of atomic spectra; Dr. Dorothy N. Davis in- 
vestigated bands in stellar spectra; Dr. John 
C. Duncan, Director of the Whitin Observa- 
tory, made photographic observations with 
the large reflectors; Dr. Leo Goldberg, of the 
Harvard College Observatory, studied certain 



MOUNT WILSON OBSERVATORY 



types of stellar spectra; Dr. Erik Holmberg, 
of the Lund Observatory, was engaged in 
nebular investigations; Dr. Dean B. Mc- 
Laughlin, of the University of Michigan, 
made an extensive study of the available 
spectrograms of novae; Dr. S. A. Mitchell, 
Director of the Leander McCormick Observa- 
tory, continued his analysis of solar eclipse 
spectra; Dr. Gunnar Randers, Fellow of Oslo 
University, carried on theoretical researches 
on stellar and nebular constitution; Dr. and 
Mrs. B. W. Sitterly worked on the light- 
curves of variable stars and on the infrared 
solar spectrum, respectively; Dr. Lyman 
Spitzer continued his investigation of M-type 
stars with the microphotometer; Dr. Toshio 
Takamine, of the Institute of Physical and 
Chemical Research at Tokyo, assisted by Dr. 
Y. Tanaka, investigated the extreme ultra- 
violet absorption spectra of several gases; Dr. 
A. E. Whitford, of the University of Wiscon- 
sin, collaborated with Dr. Stebbins in photo- 
electric measurements of early-type stars; and 
Dr. F. E. Wright, of the Geophysical Labora- 
tory of the Carnegie Institution, assisted by 
Mr. Hamilton Wright, continued his studies 
of the materials composing the moon's 
surface. 



Office and Design 

Edgar C. Nichols, instrument design; Harold 
S. Kinney, draftsman; Anne McConnell, 
bookkeeper; Gladys Adamson, stenogra- 
pher and telephone operator. 

Instrument Construction 
Optical Shop: John S. Dalton, Donald O. 

Hendrix, opticians. 
Instrument Shop: Albert Mclntire, foreman; 
Elmer Prall, Myo C. Hurlbut, Fred Scherff, 
Oscar Swanson, machinists; James Chap- 
man, pattern maker; Harry S. Fehr, cabinet 
maker; Albert Labrow, Donald W. Yeager, 
assistant machinists. 
Operation and Maintenance: Ashel N. Beebe, 
superintendent of construction; Sidney A. 
Jones, engineer; Kenneth De Huff, assistant 
engineer; Thomas A. Nelson, Earl Karr, 
Glenn C. Moore, night assistants; Anthony 
Wausnock and Mrs. Wausnock, stewards; 
Emerson W. Hartong, truck driver; Ells- 
worth L. Aden, Charles Dustman, Frank 
Lavers, Arnold T. Ratzlaff, Lester Shade, 
janitors. 

Several individuals whose names are listed 
above have been associated with the Observa- 
tory only a part of the year. 



OBSERVING CONDITIONS 



Observing conditions during the year July 
i, 1939 to June 30, 1940 were slightly below 
the average for the past 28 years. Stellar 
observations were made on 282 nights and 
solar observations on 307 days. The winter 
was exceptionally warm, with a minimum 
temperature of 23 ° F and light snowfall. The 
total precipitation, however, was 39.62 inches, 
nearly 7 inches above the average. Of this 
amount 11.6 inches fell in a single tropical 
storm during September 24-26, 1939. 

The accompanying table shows the distri- 
bution by months of the observing nights 
with the 60-inch telescope. 

As in previous years, the 60-inch telescope 
has been made available to the public for 
visual observations each Friday night. A 
popular lecture given by one of the members 
of the staff precedes the use of the telescope. 





Observations 


Month 


All 
night 


Part of 
night 


None 


1939: 

July 

August 

September 

October 

November 

December 

1940: 

January 

February 

March 

April 

May 

June 


26 
26 
13 
23 
20 
14 

6 
7 

14 
10 
23 
28 


5 

4 
5 
3 
6 
9 

10 

7 
6 

8 

7 
2 




1 

12 

5 
4 
8 

15 
15 
11 
12 
1 



Total 

Mean 28 years. . . . 


210 
204 


72 

86 


84 
75 



CARNEGIE INSTITUTION OF WASHINGTON 



SOLAR RESEARCH 



Solar Photography 



During the time when the equipment of 
the 6o-foot tower was being remodeled, the 
daily direct photographs of the sun were 
taken at the 150-foot tower with the 60-foot 
focus lens. The regular program of observa- 
tions with the spectroheliograph at the 60-foot 
tower was resumed in October 1939. 

Solar photographs were made by Hickox, 
Hoge, Nicholson, and Richardson on 307 
days. The approximate number of exposures 
of each kind was as follows: 

Direct photographs 614 

Ha spectroheliograms of spot-groups, 60- 
foot focus 210 

Ha spectroheliograms, 18-foot focus. . . . 810 

Ha spectroheliograms, 7-foot focus.... 13,000 

K2 spectroheliograms, 18-foot focus... 810 

K prominences, 18-foot focus 580 

Sunspot Activity 

During the calendar year 1939, solar obser- 
vations were made at Mount Wilson on 334 
days, on all of which spots were visible. The 
monthly means of the numbers of groups 
observed daily for the past two and one-half 
years are shown in the accompanying table. 



January. . . 
February. . 
March. . . . 

April 

May 

June 

July 

August. . . . 
September. 
October . . . 
November. 
December . 



Yearly average. 



Daily number 



9.7 

7.0 

8.7 

11.3 

9.1 

13.3 

12.3 

7.9 

9.0 

9.0 

8.4 



9.5 



1939 



8.4 

7.8 

8.1 

10.8 

11.4 

10.2 

7.5 

8.5 

9.0 

8.1 

6.7 

5.7 



8.5 



1940 



4.3 

5.2 
7.7 
6.5 
5.3 
8.3 



In 1939, 465 sunspot groups were observed, 
82 less than in 1938. This decrease occurred 
mainly in the northern hemisphere, where 



220 groups were observed in 1939 and 295 in 
1938. In the southern hemisphere 245 groups 
were observed in 1939 and 252 in 1938. 

Sunspot Polarities 

When possible, the magnetic polarities in 
each spot-group have been observed at least 
once. The accompanying table indicates the 
number of spot-groups classified from July 1, 
1939 to June 30, 1940. "Regular" groups in 
the northern hemisphere are those in which 
the preceding spot has N (north-seeking) 
polarity and the following spot S polarity. In 
the southern hemisphere the polarities are 
reversed. 





Polarity 


Hemisphere 


Regular 


Irregular 


Unclassi- 
fied 


North 

South 


88 
135 


7 
1 


62 

77 


Whole sun 


223 


8 


139 



Solar and Sunspot Spectra 

The 2 1 -foot concave-grating spectrograph 
of the Solar Laboratory has been utilized by 
Babcock to trace the characteristics of the sun- 
spot spectrum as far as A3044. Although such 
observations near the region of atmospheric 
extinction cannot add greatly to our knowl- 
edge of physical conditions in spots, they aid 
materially in the identification of lines by 
indicating their excitation potentials. Several 
spectrograms of spots in the infrared have 
also been made with this instrument and with 
the 75-foot spectrograph, and a few bright 
bridges across spots have been studied in 
detail. An interesting conclusion is that a 
bridge is sometimes accompanied by a small 
high cloud of bright iron vapor seen in 
moderate motion against the background of 
the umbra. 

Recent infrared spectrograms of the sun's 
disk taken at the Solar Laboratory are so 
much superior to previous ones that the 
region AA10500-12200 is being remeasured. 



MOUNT WILSON OBSERVATORY 



The inclusion of new and more accurate ma- 
terial will justify the delay of a year in the 
publication of the joint investigation of the 
infrared solar spectrum by Miss Moore and 
Babcock. A comparison of the estimated in- 
tensities of band lines of atmospheric oxygen, 
made by Babcock and Mrs. Coffeen, with the 
theoretical relative absorption calculated by 
Allen gives the following simple relations: 
For intensities fainter than n on Rowland's 
scale, I — A log a + B; for stronger lines, / = 
Ca + D. A, B, C, D are constants, 7 the esti- 
mated intensity, and a the computed absorp- 
tion. These equations satisfy the data unex- 
pectedly well. 

Magnetic Fields near Sunspots 

The magnetic field in sunspots is most 
intense in the umbra, where the lines of force 
are nearly perpendicular to the surface. Since 
lines of magnetic force are continuous, even- 
tually they must turn and re-enter the surface, 
presumably over a wide area outside the spot. 
The disturbed appearance of the hydrogen 
chromosphere near large spot-groups would 
indicate the presence of extensive fields of 
force in the vicinity. 

To test this question Richardson has meas- 
ured in regions outside of spots five iron 
lines, utilizing near-by atmospheric lines as 
reference standards. Eight plates measured 
both with a comparator and with a tipping- 
plate micrometer show the presence of a field 
with a sign opposite to that of the umbra, and 
about 5 per cent of its intensity. The field 
begins at a distance from the penumbra 
roughly equal to the diameter of the spot, 
and can be detected outward for five or six 
diameters. 

Measurement of Weak Solar 
Magnetic Fields 

Babcock has applied successfully to meas- 
urements of field strengths of a few hundred 
gausses the polarizing apparatus of his design, 
attached to the 21 -foot spectrograph. For still 
weaker fields he has obtained excellent results 
by adding a Lummer plate to the spectrograph. 
Tests show that magnetic fields of the order 
of 10 gausses can be studied with this arrange- 



ment, and that the equipment is exceptionally 
well adapted for investigation of the general 
magnetic field of the sun. A device has been 
developed for photographing simultaneously 
on one plate the complete interference pattern 
from both right- and left-handed analyzers; 
and a valuable feature is the thick plate of 
quartz which replaces the familiar quarter- 
wave plate of mica. By its use displacements 
of spectral lines resulting from local radial 
motions in the reversing layer are automati- 
cally eliminated. On the resulting photo- 
graphs the position of each component of 
each line is determined from 10 interference 
fringes which are relatively easy to measure; 
and the effect of any distortion of the gelatine 
film as a source of error is greatly reduced. 

In connection with this investigation Mrs. 
Coffeen has completed a survey of all identi- 
fied and analyzed solar lines between A4400 
and X6100 to aid in the selection of lines with 
the most suitable magnetic patterns. 

Solar Vortices 

An investigation by Richardson of the 
direction of whirl in hydrogen vortices on 
spectroheliograms taken from 1908 to 1939 
has confirmed the earlier work of Hale based 
on fewer data. The vortices appear to be 
hydrodynamical in origin, with their direc- 
tion of whirl determined principally by the 
solar rotation. No connection was found be- 
tween the direction of whirl and the polarity 
of spots. Open whirls greatly predominate, 
although closely wound spirals do occur. 

Chromospheric Disturbances 

Since bright chromospheric disturbances 
are almost invariably associated with spot- 
groups, it would naturally be assumed that 
their frequency is a function of the number 
of spot-groups and of the length of time they 
are observed. An examination by Richardson 
of our records for the past five years, how- 
ever, shows no evidence for such a simple 
relation. The disturbances seem to occur 
sporadically, their appearance probably de- 
pending more upon peculiarities of the indi- 
vidual spots themselves than upon sunspot 
activity in general. 



10 



CARNEGIE INSTITUTION OF WASHINGTON 



Escape of Prominences from the Sun 

Pettit has collected measurements of the 
heights of 61 prominences observed during 
eruption since 1885 and has published a cata- 
logue describing their principal features. The 
time-height plots for these prominences usu- 
ally show constant velocities increasing sud- 
denly at intervals. The only prominence 
which surpassed the critical velocity for any 
elevation above the sun was no. 47, observed 
at Lake Angelus in 1937. 

An examination of the entire material 
shows that in general the theoretical time- 
height plot of a body moving freely under 
solar gravitation deviates widely from that 
observed for prominences. In no. 47, how- 
ever, the final velocity, 728 km/sec, cannot be 
distinguished from that given by the theoreti- 
cal curve. No theory of prominence motion 
will account for eruptive prominences, but 
the uniform motions of these objects suggest 
their ultimate escape at any velocity, although 
we do not know that this velocity persists 
after the atoms lose their excited state. On 
the other hand, coronal prominences and the 
birth of streamers over sunspots suggest that 
eruptive prominences disintegrate and even- 
tually return. 

Improvements in the Spectrohelioscope 

Pettit has improved considerably the optical 
performance of the Hale spectrohelioscope by 
placing a reversing prism just behind the first 
slit, thereby making the instrument fulfill the 
correspondence condition. A mechanical im- 
provement is effected by mounting the prisms 
individually on small synchronous motors of 
the shaded-pole type with loose flywheels to 
damp out any tendency to hunt. With this 
change almost any solar spectroscope or spec- 
trograph may be converted into a spectro- 
helioscope. 

Energy Measurements in the 
Solar Spectrum 

From photoelectric tracings obtained with 
the 2 1 y 2 -foot monochromator, Pettit has de- 
termined the intensities of groups of lines in 



the regions AA3200-3300 and M.3900-4000. A 
comparison of the equivalent widths with the 
results of Mulders shows an average ratio of 
0.81. Improvements in the monochromator 
have made possible the use of slits as narrow 
as 0.02 mm and have revealed lines as faint 
as — 1 on the Revised Rowland scale. 

Ultraviolet Energy-Curve of the Sun 

Measurements carried out at Tucson in 
1 93 1 were repeated by Pettit on Mount Wil- 
son in 1934, 1937, and 1939 with improved 
equipment. Observations on 35 days in this 
period when the sky was very transparent 
yield intensity measurements for 100 ang- 
strom units between Ao.7fi and X0.292H. The 
average energy-curves for the center of the 
disk and for integrated light verify those 
obtained at Tucson, in particular a sudden 
drop of 48 per cent in intensity from A0.40 
to Ao-38[x, a nearly constant intensity from 
A.0.38 to Ao.325^, and a nearly linear fall to a 
very low value at X0.292J.1. 

The atmospheric transmission coefficients 
obtained from the measurements throughout 
the spectrum differ not more than 2 per cent 
from the Smithsonian values until the ozone 
band is reached. Measures in this region indi- 
cate an atmospheric ozone content of 0.1 cm 
at normal temperature and pressure. The 
ratio of the energy in spaces between the ab- 
sorption lines to the average in the spectrum 
was determined with the photoelectric cell 
attached to the 21 Y z -foot concave-grating 
monochromator. When these coefficients are 
applied to the thermoelectric measures the 
resulting curve for energy between the lines 
is still quite different from that of a black 
body. 

A laboratory study of the ozone spectrum 
shows that the lines in the Huggins band are 
so feeble that they will not be distinguishable 
in the solar spectrum and cannot account for 
the depressions found in the photoelectric 
energy-curves. 

Eclipse Spectrograph 

Early in 1939, the National Geographic 
Society proposed as a cooperative undertaking 



MOUNT WILSON OBSERVATORY 



II 



the construction of a spectrograph to be used 
at future solar eclipses for the photography 
on a large scale of the flash spectrum and the 
spectrum of the extreme limb of the sun. The 
instrument has been completed on this basis, 
the National Geographic Society providing 
the cost of all materials and the expense of 
nearly all the machine work, while Dunham 
of the Observatory staff has furnished the 
design and has supervised the construction. 
Some special optical and machine work has 
been done in the Observatory shops. 

The telescope is of the tower type with 
mirrors of fused quartz. The spectrograph, 
with two aluminium-on-glass plane gratings 
by Wood, has many novel features. One grat- 
ing forms a spectrum through the ultraviolet 
and blue; the other through the green, yellow, 
and red. The spectra are focused by three 
30-inch spherical mirrors of 15 feet focal 
length, placed horizontally in the bottom of 
the pit under the tower and adjusted in posi- 
tion to perform as nearly as possible like a 
single 90-inch mirror. The two parts of the 
spectrum, each 45 inches long, are focused on 
photographic plates carried on two light fabri- 
cated aluminium drums, 30 inches in diame- 
ter, carefully machined to the circular form 
required to bring every part of the photo- 



graphic emulsion into focus. These plate- 
holder drums are turned by a special Geneva 
motion which will permit 36 alternate long 
and short exposures on the solar crescent. The 
dispersion is approximately 1.8 angstroms per 
millimeter. 

The instrument may be used either with or 
without a slit. Two images of the sun are 
formed by two pairs of cylindrical mirrors, 
having focal lengths of 46 inches and 22 feet, 
respectively. These produce two elliptical 
images, in which the ratio of major to minor 
axes is approximately 6:r. The orientation 
will be chosen so that the major axis lies 
parallel to the length of the crescent. This 
arrangement should combine the advantages 
of Anderson's minified image for reducing 
atmospheric effects with the advantages of a 
larger scale in the other coordinate. Spectra 
more than an inch wide will permit accurate 
measurements of positions on the solar image. 

The war has necessitated abandonment of 
the plan of the National Geographic Society 
for sending this equipment to South Africa 
for use at the eclipse of October 1, 1940. It 
will, however, be available for later eclipses 
and meanwhile is excellently adapted for 
several fields of spectroscopic research on the 
sun. 



LUNAR AND PLANETARY INVESTIGATIONS 



Surface Features of the Moon 

Dr. Fred E. Wright, of the Committee on 
Study of the Surface Features of the Moon, 
has continued work on the method for meas- 
uring the amount of polarization in moon- 
light by use of a photoelectric cell, an alter- 
nating-current amplifier, and a rotating polar- 
izing prism. Comparison of this method with 
that in which a photoelectric cell, a direct- 
current amplifier, and a polarizing prism or a 
quartz Wollaston prism are used is now in 
progress. Some advance has also been made 
in the measurement of the slope angles of 
lunar surface features through use of the 
series of moon photographs taken in 1938 
with the 100-inch telescope. This task is time- 
consuming; but topographic maps of many 
of the craters and mountains on the moon are 



gradually being produced which will be use- 
ful later in connection with detailed physio- 
graphic studies of the moon's surface. 

The report on the results of visual measure- 
ments of the percentage polarization in light 
from different parts of the moon's surface and 
in sunlight scattered by terrestrial materials 
at different phase angles is in preparation. 
Plans had been made to_complete this report 
during the past winter; but unexpected tasks 
intervened and seriously interfered with the 
work. 

Radiation Measurements on the 
Eclipsed Moon 

Measurements made by Pettit with a ther- 
mocouple on the 20-inch telescope at the 
eclipse of October 27, 1939 on a point near 



12 



CARNEGIE INSTITUTION OF WASHINGTON 



the center of the disk showed that the tem- 
perature fell from 370 ° K to 200 ° K during 
the first partial phase and dropped slowly to 
1 75 K during totality. At the beginning of 
totality the rate of fall was 30 ° C per hour, 
but at the end of the first hour of total eclipse 
it was 7° C. A total of 39 sets of determina- 
tions both with water cell and with micro- 
scope cover glass were obtained. 

The rate of radiation is nearly proportional 
to the energy received except for very low 
temperatures. A computation based on the 
physical constants of lava and the radiation 
data shows that a surface layer 2.6 cm thick 
is all that seems to take part in the exchange 
of heat. 

Water Vapor in the Spectrum of Mars 

Seven spectrograms of Mars in the region 
near A7000, taken by Adams and Dunham 
with the coude spectrograph, have been 
studied by Adams for the presence of possible 
Martian components of the terrestrial water- 
vapor lines. Four of the spectrograms were 



taken when Mars was approaching the earth, 
and three when it was receding. Hence the 
effect of a Martian component should be to 
displace the measured wave lengths of the 
terrestrial lines between these two epochs. No 
appreciable displacement was found, and the 
conclusion is that at the center of the disk 
the amount of water vapor in the atmosphere 
cannot exceed 5 per cent of that in the atmos- 
phere of the earth. 

Satellites of Jupiter 

All the known distant satellites of Jupiter 
have been observed by Nicholson and accu- 
rate positions derived from the photographs. 

The orbit of J IX has been recomputed 
from the observations of 1939. With this 
orbit the positions of J IX were calculated 
back to the opposition of 1938 and ahead to 
that of 1940, taking into account the attrac- 
tions of Jupiter and the sun. Miss Richmond 
has assisted in the measurement and reduc- 
tion of the plates and in the computation of 
the orbit. 



MISCELLANEOUS STELLAR INVESTIGATIONS 



Trigonometric Parallaxes and 
Proper Motions 

Of the 21 stars measured by van Maanen 
for parallax, 2 have been found to lie within 
5 parsecs of the sun. These are Ross 128 and 
Luyten 789-6, with parallaxes of o".2%^ ± 
o'.'ooj and o'.'3 1 7 ± o'.'ooj, respectively. The 
total number of stars now known to lie 
within 5 parsecs is 37. In addition 13 com- 
panions to these near-by stars are known. 
Among the 21 stars measured, 17 have abso- 
lute photographic magnitudes fainter than 
+ 10, and three fainter than + 15. 

Second-epoch plates of 30 Cepheid variables 
have been obtained by van Maanen during 
the year. Thirteen of these, for which the 
interval between observations has been 10 
years or more, have been measured. The 
probable errors of the final proper motions 
determined from three pairs of exposures 
are o'.'ooi in each coordinate. The proper 



motions of 4 Cepheids have been measured 
by both van Maanen and R. E. Wilson. 

Relative Proper Motions of Variables 

Measures have been made by R. E. Wilson 
of 20 fields containing variables, mainly of 
the 6 Cephei and RR Lyrae classes, on plates 
covering intervals of 10 to 14 years. These 
were taken by van Maanen for the deter- 
mination of relative proper motions. The 
probable errors of the determinations are 
about ± o'.'ooi 3 per annum in each co- 
ordinate. 

Faint Photometric Standards 

Using the platinum half-filter method, 
Baade, with the assistance of H. F. Weaver, 
has extended the photographic scale to mag. 
20.5 in the two Selected Areas 57 and 61. 
The accuracy attained together with the 
economy of the method have led to a plan to 



MOUNT WILSON OBSERVATORY 



13 



extend the photographic scale to the same 
limit — with careful checks of the zero points 
used — in every third area of the +15° zone, 
starting with S.A. 68. In view of the urgent 
need of reliable sequences fainter than mag. 
17, it is to be hoped that arrangements can 
be made to insure completion of the program 
within the next two years. 

Photometric Catalogue of Polar Stars 

Seares and Miss Joyner have continued the 
preparation of the catalogue of magnitudes 
and colors of stars north of +8o° declination 
undertaken jointly with Dr. Ross of the 
Yerkes Observatory. The manuscript of the 
catalogue, which includes 2271 stars, is now 
ready for the printer, and the extensive dis- 
cussions of the internal consistency of the 
magnitudes are nearly finished. A gratifying 
result is the uniformity of the zero point for 
different intervals of right ascension and 
declination. The fluctuations do not exceed 
0.02 mag. and for most of the groups of stars 
tested are 0.0 1 mag. or less. Except for final 
revisions, the detailed account of the investi- 
gation given in the introduction to the cata- 
logue is also finished. 

Space Absorption 

In a survey of the problems of space absorp- 
tion Seares has suggested that the total ab- 
sorption in any direction within the zone of 
avoidance may be regarded as consisting of 
two parts, one contributed by the dust clouds 
that outline the zone, the other arising from 
the more homogeneous medium that causes 
the decrease in the counts of extragalactic 
nebulae as the zone of avoidance is ap- 
proached. The clouds are so scattered that 
their contribution is erratic and should show 
little correlation with distance. The absorb- 
ing medium, on the other hand, is a stratum 
of such uniformity that the cosecant law 
holds with good approximation down to the 
edge of the zone of avoidance, in latitudes as 
low as io° at least. The point of the sugges- 
tion is that the "stratum" is effective in pro- 
ducing absorption in still lower latitudes, 



although the simple cosecant law may no 
longer hold. The colors of B-type stars ob- 
served by Stebbins, Whitford, and Kron, and 
especially the behavior of the minimum color 
excess with increasing distance, seem to har- 
monize with this viewpoint. 

Colors of B and A Stars 

The catalogue of photoelectric colors of 
1332 B-type stars observed by Stebbins and 
Whitford has been published. The reddened 
B stars give a convenient measure of the selec- 
tive absorption in different regions, but the 
colors are also good indicators of unidentified 
supergiant B stars seen at great distances. 
The clouds of cosmic dust near the plane of 
the galaxy are so irregular that an average 
coefficient of absorption should be taken with 
caution. For this reason the values of the 
photographic absorption, 0.67 mag./kpc by 
Trumpler from open clusters, 0.85 mag./kpc 
by Joy from Cepheid variable stars, and 1.1 
mag./kpc from the B stars, are not neces- 
sarily inconsistent. Forty per cent of the 
clusters are in latitudes higher than 5 , the 
limit for the B stars, and the Cepheid varia- 
bles may also be in regions clearer than the 
average. 

Stebbins and Whitford have continued 
spectrophotometric measures of B stars to 
determine the law of space reddening 
(known to vary approximately as i/~k) and 
thus to determine the ratio of total to selective 
absorption by the interstellar material. 

Photoelectric measures of A stars near 
the north pole of the galaxy indicate an ab- 
sorption of not more than 0.10 mag. in the 
first hundred parsecs, compared with 0.25 
mag. for the total galactic absorption in that 
direction from counts of nebulae. 

Galactic Rotation and Absorption 

The radial velocities of O and B stars, 
Cepheid variables, non-Cepheid c stars, and 
interstellar gases, extending out to a true dis- 
tance of about 2000 parsecs, have been ana- 
lyzed by R. E. Wilson to determine the value 
of the galactic rotation constant, A. The 



14 



CARNEGIE INSTITUTION OF WASHINGTON 



values derived from objects at different dis- 
tances are brought into fair agreement by 
assuming a mean effective absorption of 0.65 
mag./kpc for both visual and photographic 
light. Since the distribution of the absorbing 
matter is not uniform, this assumption does 
not lead to a true value of A. A linear rela- 
tion between the observed values of A and 
the photometric distances brings all the values 
into satisfactory accord and gives a mean 
value, 

A = 17.7 ± 0.7 km/sec/kiloparsec. 

Applied to visual and photographic distance 
sequences, this value of A gives values of the 
mean absorption consistent with those derived 
on the assumption of uniform distribution. 

Luminosity Sequence for c Stars 

A study by R. E. Wilson of the mean visual 
absolute magnitudes of the non-Cepheid c 
stars shows a marked decrease in luminosity 
with advance in spectral type. The values 
of M show the following progression: Bo, 
-5.4; Ao, -4.9; Fo, -4.4; Go, -3.8; 
Ko, —2.6; K5, —2.0. 



and Miss Moore prefer the second for general 
catalogue purposes. 

Stromberg's investigation was prompted by 
the work of Russell and Miss Moore, who 
pointed out the importance of the grouping 
of the stars as affecting the calibration curves 
to be used. If M s represents the spectroscopic 
and M the true absolute magnitude, Strom- 
berg concludes that the first regression line 
(M on M s ) should be used for calibration 
when the stars are grouped on a basis depend- 
ing directly upon M s or the special spectral 
criteria which determine M K ; while the 
second regression line (M s on M) should be 
used for groupings according to M, or in 
practice according to the apparent magnitude 
m or the reduced proper motion. Spectro- 
scopic absolute magnitudes calibrated by the 
first and the second regression lines, respec- 
tively, may be denoted by M' e and M". 

The accompanying table gives the mean 
errors of M s , the symbol -ft referring to the 
values published in Mount Wilson Contribu- 
tion, No. 511, and {K and d" to the mean 
errors of M' s and M". The values d" are 
always larger than $'. 



Spectroscopic and Trigonometric 
Absolute Magnitudes 

Two investigations of the accidental and 
systematic errors in spectroscopic absolute 
magnitudes of stars of the main sequence 
have been completed, the first by Russell and 
Miss Moore, and the second by Stromberg. 
In the first of these the mean values obtained 
by grouping the spectroscopic and trigono- 
metric material according to reduced proper 
motion (which is equivalent to grouping by 
H) have been discussed in detail. The results 
substantially confirm those of an earlier 
investigation by the same authors but make 
the dispersions slightly smaller. The numeri- 
cal agreement with the values obtained by 
Stromberg by a different method is good. Of 
the two regression lines, the first of which 
corresponds to means selected according to 
the spectroscopic absolute magnitude, Russell 



0.60 
0.27 
0.45 



G0-G7 



0.51 
0.41 
0.60 



G8-K2 



0.75 

0.49 
0.65 



K3-K9 



0.42 
0.32 
0.39 



0.58 
0.56 
0.62 



Direct Photography 

Dr. Duncan used the 60-inch and 100-inch 
telescopes on a few nights during the summer 
of 1939 for direct photographic observations 
of a number of selected objects. These in- 
cluded NGC 6357, the dark nebula Barnard 
143, and one or two stellar fields, on red- 
sensitive plates; NGC 4621, 4636, and 6946, 
observed for supernovae; R Aquarii, 'and 
several stellar fields in low latitudes; and 
M 11, M 15, M 31, 1 Persei, the Orion nebula, 
and NGC 7662, photographed on Koda- 
chrome films. 



MOUNT WILSON OBSERVATORY 



15 



STELLAR SPECTROSCOPY 



Investigations in stellar spectroscopy have 
covered a very wide variety of objects, rang- 
ing from faint supernovae to the brightest 
stars. A new spectrograph of unusual design 
which has been under construction in the 
instrument shop and is nearing completion 
should greatly facilitate observations of faint 
stars and nebulae with somewhat higher dis- 
persion than that hitherto employed. Two 
light flint prisms and a collimating mirror 
are used with cameras of the Schmidt or lens 
type ranging in focal length from 3 to 18 
inches. The transmitting surfaces in the 
entire optical system have been treated with 
an evaporated coat of fluorite with a marked 
gain in light efficiency. The same process is 
now being applied to the surfaces of the 
prisms and lenses in the other stellar 
spectrographs. 

Another small spectrograph of the "broken" 
type for use at the Newtonian focus of the 
large reflectors has been completed and used 
during a part of the year. The collimator is 
a parabolic mirror and the beam of light 
between the collimator and prisms is deviated 
by an inclined plane mirror near the focus of 
the telescope. The plane mirror has a hole 
near the center, sufficiently large to transmit 
the beam from a long slit. Comparisons with 
the small Cassegrain spectrograph indicate 
that for equal dispersions the field and the 
photographic efficiency of the two instru- 
ments are essentially the same, but that much 
fainter objects can be seen and centered at the 
Newtonian focus. An important practical ad- 
vantage is that by removal of the slit the 
Newtonian spectrograph can be used as a 
slitless instrument to record small-scale spectra 
during a program of direct photography 
without the necessity of changing cages on 
the telescopes. 

The 114-inch Schmidt camera used in the 
coude grating spectrograph at the 100-inch 
telescope has proved to be remarkably efficient 
in observations of bright stars with high dis- 
persion. The absence of glass in the optical 
system leads to excellent transmission in ultra- 
violet light, and exposure times have proved 



to be considerably shorter than expected. 
Stars of the 4th magnitude are now readily 
observable with a linear dispersion of 2.9 
angstroms to the millimeter. 

The so-called "blind" spot in the center of 
the extrafocal beam of the reflectors due to 
auxiliary mirrors makes it impossible to use 
spectra taken with the image slicer and cylin- 
drical lens for photometric purposes. This is 
because the cylindrical lens is used to focus 
the grating upon the photographic plate. To 
overcome this difficulty Dunham has de- 
signed a system of quartz prisms of small 
angle for use at the coude focus of the 100- 
inch telescope. Two prisms placed 56 inches 
above the focus direct a portion of the eastern 
and western areas of the circular beam into 
the blind spot, where two other small prisms 
receive the light and send it to the slit and 
collimator. The focus of this light is the same 
as that of the main beam, the system is achro- 
matic, and through prisms of suitable size 
the blind spot should be completely elimi- 
nated. The equipment is now under con- 
struction and will soon be tested. 

Dunham has also designed an instrument 
for providing satisfactory calibration spectra, 
especially in the ultraviolet region, at the 
coude focus of the 100-inch telescope. The 
device resembles in principle the van Cittert 
monochromator, in that it employs two spec- 
trographs in tandem. A single aluminized 
spherical mirror and a 30° quartz prism with 
aluminized rear surface are used, and the 
spectral distribution is finally regulated by a 
diaphragm or an unevenly aluminized trans- 
mission plate placed at the focus. 

Approximately 1400 stellar spectrograms 
have been obtained with the various instru- 
ments during the year. 

Radial Velocities 

Measurements of the radial velocities of 
variable stars of types Me and Se have been 
continued by Merrill and Miss Burwell, and 
this program is nearing completion. About 
i=;o additional stars have been observed since 



i6 



CARNEGIE INSTITUTION OF WASHINGTON 



the last statistical discussion, and many of the 
previous objects have been reobserved. Espe- 
cial attention is being given to the relative 
displacement of emission and absorption lines, 
and to lines in the ultraviolet region. 

Radial-velocity observations and measure- 
ments of stars in the Selected Areas have been 
continued regularly by Stromberg, Christie, 
and Miss Lowen, and one or more spectro- 
grams have now been obtained for 257 of 
the 297 stars on the program. A star in this 
list, BD +30°26n, has the remarkable 
radial velocity of —278 km/sec. A number 
of B- and A-type stars in special regions of 
the sky are under observation at the request 
of Dr. Bok, of the Harvard College Observa- 
tory, the measured radial velocities serving as 
an aid in the determination by his method of 
velocities from spectra taken with the objec- 
tive prism. 

The first known spectroscopic binary hav- 
ing a spectrum of the Wolf-Rayet type was 
discovered by O. C. Wilson and has been 
under investigation by him. Two spectra are 
present, one of type WN5 and the other of 
early B. The minimum mass of the Wolf- 
Rayet star is 9.74 times the sun's mass, and 
that of the B star, 24.8. The orbits of the 
two stars show a difference of 90 km/sec in 
the positions of the y axes, which is believed 
to represent a shift in wave length of the 
Wolf-Rayet bands. If, as some evidence from 
the work of Beals indicates, such a shift may 
be a common if not universal phenomenon 
in Wolf-Rayet spectra, it will be a matter of 
fundamental interest to determine its source. 

Another remarkable star is 48 Librae (HD 
142983). Merrill and Sanford found that 
between 1935 and 1939 the radial velocity 
derived from the metallic lines and the ultra- 
violet hydrogen lines decreased about 100 
km/sec and then returned to its previous 
value. Meanwhile the hydrogen lines H(3, 
Hy, and Hb were displaced only about one- 
half as much. At present both groups of lines 
are showing a tendency to give algebraically 
higher values of the velocity. 

The bright star Rigel and its companion 
have been studied by Sanford with the coude 
spectrograph. The known variation in the 



radial velocity of Rigel has been confirmed 
but no definite period has as yet been derived. 
The H and K lines each show a sharp com- 
ponent, apparently of stellar origin, and the 
structure of the main H and K lines seems to 
be complex. The spectrum of the companion 
to Rigel has numerous lines which are defi- 
nitely double at times. It is presumably a 
spectroscopic binary with a period, not as yet 
precisely determined, of a few days. 

Measurements of the displacements of the 
H and K lines in the spectra of the Cepheid 
variables t, Geminorum, T) Aquilae, and o 
Cephei have been continued by Adams and 
Joy. The velocity-curve for the first of these 
stars is nearly completed. 

Thirty-seven spectrograms of Arcturus by 
Adams with the coude spectrograph have 
yielded a solar parallax of 8'/8o5 ± o'/oo7. 

Spectra of Variable Stars 

Variables of the SS Cygni class are of excep- 
tional spectroscopic interest because of their 
recurrent nova-like outbursts in semiperiodic 
cycles. Observations are difficult because of 
faintness and irregularity in light-variation. 
Six stars of this class have been observed by 
Joy; at maximum of light two show only a 
continuous spectrum; three, a continuous 
spectrum with undisplaced emission lines of 
hydrogen 10 angstroms wide; while the re- 
maining star, SU Ursae Majoris, shows emis- 
sion lines both of helium and of hydrogen 
on a continuous background. At minimum 
of light, however, absorption lines correspond- 
ing to those of type dG3 appear in the spec- 
trum of SU Ursae Majoris, and the emission 
lines are strengthened. This observation indi- 
cates that these stars are dwarfs, the only 
known stars of low luminosity with intrinsic 
variability. 

Joy has also observed the spectra of a large 
number of variables with intermediate or 
irregular periods, several eclipsing variables, 
and Cepheid variables in the globular star 
clusters M 2, M 3, M 10, and M 12. 

Several observers have studied special fea- 
tures of the spectra of long-period variables. 
Merrill has given particular attention to the 



MOUNT WILSON OBSERVATORY 



17 



molecular bands in the visual region of some 
typical variables at various phases of light, 
more especially the monoxides of Ti, Zr, V , 
Sc, and Y. Joy has continued his observations 
of the character and changes of the emission 
lines in the spectrum of Ceti; and Adams, 
using the high dispersion of the coude spectro- 
graph on this star when near maximum, has 
examined the structure of some of the bright 
hydrogen lines and has measured the displace- 
ments of absorption lines of various classes. 
A definite correlation seems to exist between 
radial velocity and the lower excitation level 
of the lines involved. The doubling of numer- 
ous absorption lines characteristic of super- 
giant M-type stars has also been found in the 
spectrum of Ceti. 

An important contribution to our knowl- 
edge of this class of stars is the monograph 
by Merrill on "Spectra of long-period variable 
stars," which will appear in the series issued 
by the Astrophysical Journal. 

Bands in Stars of Spectral Types 
M, N, and R 

Closely associated with studies of long- 
period variables has been the investigation by 
Miss Dorothy Davis of molecular bands in 
the spectrum of the bright M-type star (3 
Pegasi. High-dispersion spectrograms have 
made it possible to study this star in great 
detail, and the wave lengths of about 5800 
lines have been measured in the region 
A3780— A6780. Visual estimates of intensities 
have been completed and identifications have 
been established for many molecular lines and 
bands. These include, roughly in order of 
strength: TiO, SiH, MgH, AlH, ZrO, ScO, 
BO, SiF, SiN, CH, and CN. Some of these 
have been identified for the first time in 
stellar spectra. 

Sanford has found evidence for the pres- 
ence in N-type spectra not only of bands due 
to the carbon isotopes C 12 C 13 and C 13 C 1& , 
but also of bands of C 13 N 14 , analogous to the 
C 12 ZV 14 bands. In the red region of the spec- 
trum various N-type stars are found to show 
marked differences in the structure and 
strength of the Swan bands. Similar differ- 
ences are shown by variables at various phases 
5 



of their light-curves. The intensities of the 
D lines of sodium differ by a factor of 25 
in various stars. A set of bands not previously 
identified seems to agree in position with 
bands given by metallic Ca in the electric 
furnace and may possibly be due to Ca 2 . 

Be Stars 

Numerous additional stars of early type 
with emission lines have been discovered on 
photographs made by William C. Miller with 
the 10-inch telescope and objective prism. 
These are being investigated with slit spectro- 
graphs by Merrill and Miss Burwell, and the 
results will be incorporated into a supplement 
to the "Catalogue and bibliography of stars 
of classes B and A whose spectra have bright 
hydrogen lines," published in 1933. 

X, AURIGAE 

This remarkable star was observed exten- 
sively by O. C. Wilson at its eclipse in 1939- 
1940, particularly during ingress. About 60 
spectrograms were obtained with the 32-inch 
Schmidt camera of the coude spectrograph 
and about one-fourth of these have been 
traced with the microphotometer. Curves of 
growth have been derived for various levels 
in the star's atmosphere, and the turbulence 
and the excitation temperature, calculated for 
four and three levels, respectively, are found 
to increase outward from the photosphere. 
Ultimately it should be possible to derive the 
electron pressures and the total density with 
fair accuracy. 

The light-curve of Z, Aurigae was observed 
by Christie throughout the eclipse, and its 
form seems to be well established. 

Interstellar Lines 

Several investigations have dealt with the 
lines due to the absorption of gases in inter- 
stellar space. In the course of one of these 
Sanford has found that the star HD 190429 
N, which shows double interstellar H and K 
lines, has single D lines, thus indicating a 
marked difference in the distribution of ion- 
ized calcium and neutral sodium gases along 
the line from the sun to the star. 



i8 



CARNEGIE INSTITUTION OF WASHINGTON 



The interesting problem of the concentra- 
tion of ionized calcium gas in the neighbor- 
hood of the sun has been studied by Dunham 
through measurements of the intensity of the 
interstellar K line in the spectra of some of 
the nearest early B-type stars. Spectrograms 
on fine-grained plates were made with the 
114-inch camera of the coude spectrograph. 
A faint interstellar line was measured in the 
spectrum of a Virginis, which has a distance 
of the order of 55 parsecs. The indicated con- 
centration of Ca 11 is 3 X io~ 10 ions per cubic 
centimeter. No line could be detected in r\ 
Ursae Majoris, at a distance of about 65 par- 
secs. The concentration must differ by a 
factor of at least 2 along the paths to these 
stars, although the mid-points of the paths 
are separated only some 30 parsecs. This 
indicates that the distribution of interstellar 
material is extremely irregular even over short 
distances. The value for the density of Ca 11 
is much less than that found by Merrill and 
Sanford for distant stars in the general direc- 
tion of the Milky Way. 

Among the unidentified interstellar lines 
discovered a few years ago at Mount Wilson 
is a prominent line at A.4300.3. The sugges- 
tion was made by Swings and Rosenfeld that 
it might be due to the molecule CH, but no 
satisfactory identification could be based upon 
a single line. Recently McKellar, assuming 
A.4300 to be due to CH at very low tempera- 
tures, predicted the presence of three fainter 
lines, and calculated their relative intensities. 
All four lines arise from the ground electronic 
state of the molecule and are the only ones 
sufficiently strong to present some possibility 
of observation as interstellar lines. 

Although the three predicted lines had not 
been observed in any stellar spectrum, it 
seemed possible that they might appear on a 
reasonably fine-grained plate of sufficient con- 
trast. Fortunately a bright star, t, Ophiuchi 
of magnitude 2.7, in which A4300 is promi- 
nent, was available. Spectrograms taken by 
Adams with the 114-inch coude spectrograph 
showed three lines close to the predicted posi- 
tions and with the proper relative intensities. 
Measurements of wave length gave an aver- 



age difference from the laboratory values of 
0.03 A, a quantity well within the accuracy 
of the determinations. The agreement of the 
four lines in wave length and relative inten- 
sity, and the fact that only those lines appear 
as interstellar lines which should be present 
on the basis of theoretical considerations, 
afford conclusive evidence of the correctness 
of the identification of CH. This confirma- 
tion of McKellar's prediction provides the 
first definite evidence of the existence of 
molecules in interstellar space. 

The situation regarding the identification 
of CN is of equal interest. Two lines listed 
by McKellar at 7,3874.0 and A3874.6 are cer- 
tainly present as interstellar lines with wave 
lengths agreeing closely with the laboratory 
values. Two other very faint lines have been 
measured at A.A.3579.98 and 3875.78 which also 
agree closely with two faint lines predicted 
by McKellar at AA3579.98 and 3875.77. The 
evidence for the presence of interstellar CN 
is, therefore, essentially as conclusive as that 
for CH. As McKellar has pointed out, the 
presence of the line A.3874.0 is especially inter- 
esting since it arises from the R(i) rotational 
level as compared with the R(o) level of 
7.3874.6. The difference amounts to 0.00047 
volt, and the relative intensities of the two 
lines afford a means of calculating the actual 
"effective" temperature of interstellar space. 
This is about 2?5 on the absolute scale. 

The spectrograms of "C, Ophiuchi show a 
previously unobserved line of moderate inten- 
sity at ^3745.3 and also close interstellar com- 
ponents to the prominent interstellar H and 
K lines of calcium. 

mlcrophotometric studies of 
Stellar Spectra 

Tracings of spectra made with the micro- 
photometer have been used to great advan- 
tage in nearly all the stellar investigations. 
The high-dispersion spectrograms taken with 
the coude spectrograph are being used by 
Dunham and Miss Carlson in studies of line 
intensities and contours in the ultraviolet 
region. Especial attention has been given to 
the spectrum of a Cygni. 



MOUNT WILSON OBSERVATORY 



19 



GALACTIC NEBULAE 



R Aquarii 



Hubble reports that comparisons of direct 
photographs, over an interval of 17 years, 
show definite changes in the nebulosity sur- 
rounding R Aquarii. Outward motion is 
evidently involved, but its precise nature is 
not yet clear and will be investigated further. 

Expansion of the Cygnus Loop 

Angular motions in the great loop in 
Cygnus (NGC 6960-6992) have long been 



observed, and have been interpreted as expan- 
sion of the loop. An attempt, by Humason, 
to determine the linear velocity of expansion, 
using small-scale spectra, was unsuccessful. 
He has now repeated the investigation, using 
several spectrograms of considerably larger 
dispersion, but the results are again negative. 
They suggest, as a conservative conclusion, 
that the velocity of expansion is definitely less 
than 100 km/sec. The corresponding dis- 
tance, indicated by the angular expansion, 
appears to be less than 300 parsecs. 



EXTRAGALACTIC NEBULAE 



Spectra of Extragalactic Nebulae 

Spectra of nearly 300 nebulae are now 
available at Mount Wilson, the great majority 
having been obtained by Humason. Most of 
these spectra are on a small scale (500 or 
1000 A/mm at Hy) and, while they have 
served admirably for the preliminary survey 
of a new field, they have permitted the recog- 
nition and study of only the more conspicuous 
phenomena (law of red shifts, velocity dis- 
persions in clusters, etc.). Emphasis has now 
shifted from surveys to special problems. 
Some of these problems must necessarily be 
investigated with small-scale spectra, but 
others are assuming an importance which 
requires much larger scales. 

The practical aspects of the new problems 
have been explored during the year, with 
large-scale spectra of M 31, M 32, and M 33, 
intermediate-scale spectra (175 A/mm at 
Hy) of 22 nebulae of various types, and a 
few grating spectra in the red. The results 
have led to the formulation of an extensive 
program which will be carried out with the 
new, recently completed spectrograph which 
gives dispersions of 40 A/mm and upward 
at Hy. This instrument and the small-scale 
spectrograph for use at the Newtonian focus 
are described briefly under "Stellar spectros- 
copy." 

Confirmation of a Large Red Shift 

Humason has obtained an important spec- 
trogram of a faint nebula in the Bootes 



cluster which, in a typical case, fully confirms 
the identification of details previously made 
on a plate of very small scale. The nebula, 
m vg = ij.S, had been observed with a wide 
slit and a dispersion of 1000 A/mm at Hy, 
the nebular spectrum being superposed on the 
sky spectrum. The new exposure, obtained 
with a narrow slit and double the former 
dispersion, materially improves the definition, 
and suppresses the sky spectrum. Four fea- 
tures can be definitely identified, the G band, 
H and K, and the complex band ^3830±. 
The measured displacements, corresponding 
to a velocity of +39,000 km/sec, confirm the 
value previously derived from the small-scale 
spectrum, and definitely establish an extreme 
point on the velocity-distance curve. The 
result inspires greater confidence in the identi- 
fication of details in all the earlier spectra 
with large red shifts. 

The new spectrum records some of the 
more conspicuous emission lines of mercury, 
which presumably originate in the valley 
lights. This effect has been increasing in late 
years, and is now generally found on all 
spectrograms with long exposures. 

Miscellaneous Results 

Humason has also successfully recorded the 
spectrum of an extremely faint emission patch 
in IC 1613 (a member of the Local Group), 
and has investigated the spectrographic rota- 
tion of the typical E7 nebula NGC 31 15, on a 
considerably larger scale than that previously 
employed. 



20 



CARNEGIE INSTITUTION OF WASHINGTON 



Masses of Nebulae 

Investigations of two unsolved fundamental 
problems, namely, the order of nebular masses 
and the direction of rotation in spirals, were 
initiated during the year. Statistical masses 
may be derived from radial velocities of com- 
ponents of double nebulae by familiar 
methods used in the case of double stars, and, 
over a period of years, Humason has been 
assembling the requisite data. Hubble has 
now analyzed these data and finds that the 
masses are so small that the mass effects can- 
not be isolated from the uncertainties of the 
velocities. The results suggest an upper limit 
of the order of io 10 suns. A new program 
has been initiated by Hubble and Humason 
for the purpose of assembling more precise 
velocities. The first ro pairs observed seem 
to confirm the low order of mass suggested 
by the less accurate velocities. 

Rotation of Nebulae 

The problem of the direction of rotation re- 
quires spectrographic observation of nebulae 
in which the spiral patterns can be traced and 
the direction of the tilt can be unambiguously 
determined. Such cases are very rare, but, 
after a complete survey of the iooo brightest 
nebulae in the northern sky, Hubble has now 
found three objects which seem to meet the 
specifications. He has already observed the 
spectrographic rotation in one case, NGC 
4258 (the arms appear to trail behind as the 
spiral rotates), and the other objects will be 
observed during the coming season. 

Dwarf Irregular Nebulae 

Increasing evidence that absolutely faint 
irregular nebulae of the Magellanic Cloud 
type are characterized by low surface bright- 
ness and small color index suggests the possi- 
bility of using these criteria for locating such 
dwarf systems. Baade has tested the sugges- 
tion by examining with the 100-inch telescope 
a list of possible cases assembled by Zwicky 
with the 18-inch Schmidt reflector on Palo- 
mar. Two of the objects, both uncatalogued, 



prove to be highly resolved, near-by, irregular 
systems, and, intrinsically, the faintest known 
of the extragalactic nebulae. The 1940 posi- 
tions, the moduli (derived from the brightest 
stars), and the absolute magnitudes are 
shown in the accompanying table. 



Sextans. 
Leo .... 



10 h 
9 



8 m l 
55.9 



- 4° 
+ 31 



24' 
2 



(m-M) 



22.7 
22.9 



■10.0 

8.7 



Classification of Nebulae 

The classification, on large-scale reflector 
plates, of the 800 Shapley-Ames nebulae 
brighter than the 13th magnitude, and north 
of — 30 ° declination, has been completed by 
Hubble, and considerable progress has been 
made in the quantitative analysis of their 
characteristics. In addition, some 200 other 
nebulae, either slightly fainter than the 13th 
magnitude or south of — 30 declination, 
have been classified as a supplement to the 
main sample collection. An examination of 
the small-scale distribution is under way, in- 
cluding the relative frequencies of groups of 
different populations. It appears that isolated 
nebulae are relatively rare, the percentages 
ranging from about 5 among elliptical 
nebulae to 15 among late-type spirals. 

Structural Forms of Nebulae 

Randers has examined the structural forms 
of nebulae from a hydrodynamical point of 
view. The great variety of types which differ 
fundamentally from both normal spirals and 
elliptical nebulae indicates that current 
theories of the formation of spiral arms by 
the ejection of matter from rotating lenticular 
nebulae are not sufficient for an explanation 
of nebular evolution. The patterns of circular 
rings and systems of rings, found in spirals 
as well as in the so-called "transitional" type, 
may be an important step in the evolution. 
The active agent in the formation of rings 
appears to be viscosity in a differentially 
rotating system. 



MOUNT WILSON OBSERVATORY 



21 



Distribution of Nebulae 

Holmberg has made the first quantitative 
measures of the clustering tendency of nebu- 
lae from their observed distribution in the 
sky. By an analysis of angular distances be- 
tween nebulae in the General Catalogue and 
the Shapley-Ames Catalogue, he has made a 
statistical separation between physical and 
optical companions and has determined 
dimensions and relative frequencies of groups 
with different numbers of components. 

The observed grouping, from an evolu- 
tional point of view, might represent a stage 
in either the formation or the disintegration 
of clusters. Holmberg has examined the for- 
mer alternative in detail. Assuming average 
masses of the order of io 11 suns, average space 
velocities of the order of 320 km/sec, and 
effective capture distances of 4000 parsecs, he 
finds that a process of clustering by capture 
from an originally random distribution of 
nebulae in a stationary universe would lead 
to a distribution similar to that actually ob- 
served, in a period of the order of 2 X io 12 
years. The assumptions would also account 
for the observed numbers of high velocities, 
ascribing them to temporary members of the 
clusters. 

A structural evolution along these lines 
does not seem likely in a rapidly expanding 
universe unless the expansion is assumed to 
be of a very irregular nature. 

Spectra of Supernovae 

Minkowski has observed the spectra of the 
three supernovae discovered during the year in 
NGC 6942 (No. 2), 5907, and 4725, and, in the 
last two, has recognized a new type of super- 
nova. These objects are provisionally called 
'type II," and those previously investigated 
"type I" (represented, for instance, by the 
supernova in IC 4182). 

The type II object in 4725 is unusually well 
observed, having been followed closely for 
about four months after maximum. Up to six 
days after maximum the spectrum was con- 
tinuous, having high intensity in the blue, 



with no visible structure other than suspected 
emission near Ha. Thereafter, the continuous 
spectrum faded, and broad emission bands 
developed which, from about three weeks 
after maximum, continued to dominate the 
spectrum. Some of the bands are evidently 
complex, and the great width of the indi- 
vidual bands (velocities of 5000 km/sec or 
more on the assumption of expanding shells) 
renders complete identification difficult. How- 
ever, the spectrum as a whole resembles that 
of normal novae in the transition stage, al- 
though the hydrogen bands are relatively faint 
and forbidden lines are either extremely faint 
or missing. 

Supernovae of type II differ from those of 
type I in the transition from a continuous 
spectrum at maximum to an emission spec- 
trum whose main constituents can be readily 
identified. As compared with normal novae, 
supernovae of type II show a considerably 
earlier type of spectrum at maximum, and 
hence a higher surface temperature (order of 
40,000°); and the later emission spectrum 
indicates greater velocities of expansion and 
higher levels of excitation. 

The obvious suggestion that supernovae of 
type II are intermediate between ordinary 
novae and supernovae of type I will be 
investigated. 

Light-Curves of Supernovae 

Baade has derived light-curves of the five 
supernovae in NGC 4621, 4636, 6946 (No. 2), 
5907, and 4725. The curves of the first three 
are similar to the normal curve representing 
most of the supernovae previously investi- 
gated. The two objects of Minkowski's type 
II, namely, those in NGC 5907 and NGC 
4725, are abnormal in showing a conspicuous 
shoulder in the light-curve following maxi- 
mum. On the basis of this criterion, Baade 
has added the supernovae in 4273 and 5236 
to the new group. These four objects, at 
maximum, were systematically fainter than 
those of type I, averaging less than 
M n „= — 12. 



22 



CARNEGIE INSTITUTION OF WASHINGTON 



LABORATORY INVESTIGATIONS 



Furnace and Arc Spectra 

The study of the spectrum of gadolinium, 
including segregation of the Gd i and Gd n 
spectra, measures of wave length, intensity 
estimates, and temperature classification, has 
been continued by A. S. King, with much 
assistance in wave-length measurement by 
E. F. Adams. The present list, subject to 
checking and probable extension in the infra- 
red, contains nearly 6000 lines. Supple- 
mentary spectrograms made during the year 
have been chiefly in the ultraviolet, where 
absorption furnace spectra show low-level 
lines beyond the limit of emission spectra, 
and in the infrared. A more exact measure- 
ment of the numerous faint lines needed in 
the completion of multiplet structure is the 
chief work remaining. 

The temperature classification of the 
stronger Gd 1 lines was used by Russell, in 
collaboration with Dr. Albertson, of the 
Massachusetts Institute of Technology, in 
beginning a term analysis which has brought 
out the main features of the spectral structure. 
The triad of PDF terms of multiplicity 11, 
and the high 11 D° term with which they 
combine, have been found. This is the high- 
est multiplicity which is theoretically to be 
anticipated in any spectrum. 

A further study of titanium oxide and 
carbon bands has been made by A. S. King, 
including the conditions for the appearance of 
bands due to the isotope C 13 . Numerous 
additional photographs of the arc and furnace 
spectrum of scandium have been made, with 
an extension into the infrared beyond the 
range already studied. The considerable 
amount of this rare substance available has 
made it possible to obtain spectrograms of 
such intensity as to add materially to the lines 
previously known. 

Measurement of /-values 

The measurement of the relative and abso- 
lute /-values of spectral lines by the method 
of total absorption has been continued by 
R. B. King. In addition to values for lines of 



Cd 1 and Cu 1 previously reported, the abso- 
lute /-values have been obtained for the Tl 1 
lines A3776, A5350, and for a number of lines 
belonging to two multiplets arising from the 
normal a 5 D state of Fe 1. The latter will 
serve to place on an absolute scale the more 
extensive /-values for Fe 1 lines derived from 
measurements of absorption and emission 
spectra. The measurement of relative /-values 
for lines in the spectra of Ni 1 and V 1 has 
been continued. 

The accurate control of temperature and 
vapor pressure in the furnace over the wide 
range used in measurements of absolute 
/-values has permitted a rather detailed study 
of the whole course of the curve of growth of 
the absorption lines Cd A3261 and Tl A3776. 

Intensity Measurements of Emission 
Lines of Iron 

Through a study of the conditions under 
which accurate photometric treatment of 
emission lines of iron can be carried on, 
Minkowski and R. B. King have found that, 
if the pressure in the furnace is lowered to 
20 mm of mercury or less, considerable varia- 
tion of the relative intensities in at least two 
multiplets can be observed. The nature of 
the deviations from thermodynamical equi- 
librium which are responsible for these varia- 
tions has not yet been established definitely. 
At least one of these multiplets (a 5 F — z 5 D°) 
seems to show differences of relative intensi- 
ties of a similar type in the spectra of certain 
stars. At higher pressures purely thermal 
excitation of emission lines is obtained. The 
results for relative /-values of emission iron 
lines are in excellent agreement with the 
values obtained by R. B. and A. S. King from 
absorption lines. The measurements will now 
be extended to lines of higher excitation 
which are not accessible as absorption lines. 

Extreme Ultraviolet Spectra of Gases 

A study of the absorption spectra of hydro- 
gen and rare gases in the region of the ex- 
treme ultraviolet was made by Takamine and 



MOUNT WILSON OBSERVATORY 



23 



Tanaka, using a vacuum spectrograph pro- 
vided with a 20-cm concave grating at grazing 
incidence. That the helium continuum be- 
tween A500 A and A.900 A is of molecular ori- 
gin was indicated by its absence in absorption 
even at fairly high pressures. The Lyman 
series of hydrogen was obtained in absorption 
up to its eighth member. For neon, most of 
the lines belonging to the resonance series 
were seen as absorption lines, and in the case 
of helium, the broadening of the resonance 
line A.584 A was found to be quite similar to 
its structure in emission. 

Ruling Machines 

The driving connection for the plate car- 
riage and the operating nut of antifriction 
metal have been completed for the small 
machine and ruling tests show that these 
parts, together with the new screw, are func- 
tioning satisfactorily. With the suppression of 
the larger errors, the smaller ones of the 



accidental type are seen to be related to one 
of two or three independent causes which 
may operate simultaneously. The remaining 
errors of the periodic type are located in the 
spacing gear. Ghosts arising from these are 
unimportant in the first order but are un- 
desirably strong in the third and higher 
orders. Through an extension of the method 
already used for removing larger errors from 
the gear these ghosts can doubtless be reduced 
greatly in intensity. 

Films of evaporated duralumin (Al, Mg, 
Cu, Mn) have been found superior in some 
respects to those of pure Al, as they tear less 
easily and adhere more firmly to the glass. 
Through the generosity of Professor Planiol 
(Ecole Normale Superieure, Paris), a few 
diamonds from the Dutch East Indies have 
been presented to the Observatory. These are 
considered by expert judges to be harder than 
any other known diamonds; and they are 
proving most valuable as ruling tools. 



CONSTRUCTION AND MAINTENANCE 
Design and Instrument Shop Optical Shop' 



Two major instruments, completely de- 
signed during the year and later placed under 
construction in the instrument shop, have 
been the new two-prism spectrograph for use 
at the Cassegrain focus of the 100-inch tele- 
scope, and the 10-inch photovisual telescope. 
The spectrograph has been completed and 
placed in use. The reconstruction of the 
equipment for the 60-foot tower telescope has 
also been finished. Other important apparatus 
has included the mounting for the 36-inch 
mirror of the coude spectrograph, a new drive 
for the 20-inch telescope, a scanning com- 
parator, new parts for the interferometer 
spectrograph, and the mirror cells and some 
other portions of the large eclipse spectro- 
graph. Repairs and improvements to exist- 
ing instruments have required about 20 per 
cent of the time of the instrument shop. 

E. C. Nichols, assisted by H. S. Kinney, has 
been in charge of design, and Albert Mclntire 
has supervised the work of the instrument 
shop. 



John S. Dalton and Donald O. Hendrix 
have carried on the optical work, completing 
the figuring of numerous prisms and lenses 
and two plane mirrors, each about 20 inches in 
diameter. Much of the difficult work of figur- 
ing the components of the 10-inch photovisual 
lens has been finished by Dalton. Hendrix 
has developed most successfully methods for 
controlling the deposition of evaporated films 
upon optical surfaces to reduce loss by reflec- 
tion, and has applied them to most of the 
optical parts of the stellar spectrographs. 

By special arrangement with the California 
Institute of Technology, the 72-inch spherical 
mirror F/2.5 for the 48-inch Schmidt tele- 
scope on Palomar Mountain has been figured 
in the Observatory optical shop. The entire 
work of grinding and polishing was com- 
pleted by Hendrix and Dietz in 21 weeks. 
The difficult task of figuring the 48-inch cor- 
recting plate for this instrument will soon 
begin. 



2 4 



CARNEGIE INSTITUTION OF WASHINGTON 



Buildings and Grounds 

The reconstruction of the 6o-foot telescope 
during the summer of 1939 involved moving 
the tower a distance of 4 feet and considerable 
new structural steel and concrete construction. 
This work was done under the superinten- 
dence of A. N. Beebe. The complicated 
system of electric wiring for the instrument 



was installed completely by Sidney Jones, 
engineer, and Kenneth De Huff, assistant 
engineer. The 60-foot tower and the dome 
of the 6-inch telescope have been repainted 
with aluminum paint and many small repairs 
have been effected. 

In Pasadena all the main buildings have 
been repainted. 



THE LIBRARY 



During the past year 269 volumes have 
been added to the library, 55 by gift, 63 by 
purchase, and 151 by binding, making a total 
of 14,301 volumes, with about 12,000 pam- 
phlets and 2500 lantern slides. The amount of 
material received from the 200 observatories 



and research institutions which ordinarily 
send their publications to the library has been 
greatly reduced this year. Also because of 
war in Europe the number of periodicals 
usually received has dropped from 134 to no, 
of which 34 are gifts or exchanges. 



BIBLIOGRAPHY 



Adams, Walter S. Survey of the year's work 
at Mount Wilson. Pubs. A. S. P., vol. 52, 
pp. 5-12 (1940). 

Ferdinand Ellerman. Pubs. A. S. P., 

vol. 52, pp. 165-168 (1940). 

Spectra of bright stars with high dis- 
persion. Read at Berkeley meeting, A. A. S. 
(1939); (abstract) Pubs. A. A. S., vol. 9, 
p. 247 (1939). 

The work of the Mount Wilson Obser- 
vatory. Jour. R. A. S. Canada, vol. 34, pp. 
198-205 (1940). 

and Alfred H. Joy. The behavior of the 



calcium H and K lines in the spectrum of 
L Geminorum. Read at Berkeley meeting, 
A. A. S. (1939); (abstract) Pubs. A. A. S., 
vol. 9, p. 254 (1939). 

Anderson, John A. The two-hundred-inch tele- 
scope. Read at Berkeley meeting, A. A. S. 
(1939); (abstract) Pubs. A. A. S., vol. 9, 
pp. 247-248 (1939). 

and R. W. Porter. The 200-inch tele- 
scope. The Telescope, vol. 7, pp. 29-39 
(1940). 

Babcock, Harold D. Some transient features of 
a sunspot spectrum. Read at Delaware 
meeting, A. A. S. (1939); (abstract) Pubs. 
A. A. S., vol. 10, pp. 4-5 (1940). 

Carlson, Dorothy. Some corrections to Dreyer's 
catalogues of nebulae and clusters. Astro- 
phys. Jour., vol. 91, pp. 35 ~359 (!94°); 
Mt. W. Contr., No. 626. 

Christie, William H. Integrated photographic 
magnitudes of sixty-eight globular clusters. 
Astrophys. Jour., vol. 91, pp. 8-19 (1940); 
Mt. W. Contr., No. 620. 



Davis, Dorothy N. The line X5015 of He 1 
in the spectrum of Zeta Tauri. Pubs. A. S. 
P., vol. 52, pp. 147-148 (1940). 

The ScO band at X4858 in Ceti. Pubs. 

A. S. P., vol. 52, pp. 207-208 (1940). 

SiH in the sun and late-type stars. Read 

at Seattle meeting, A. S. P. (1940); (ab- 
stract) Pubs. A. S. P., vol. 52, p. 280 (1940). 

Dunham, Theodore, Jr. Knowledge of the 
planets in 1938. Reprinted from Coopera- 
tion in research, Carnegie Inst. Wash. Pub. 
No. 501 (1938); Pubs. A. S. P., vol. 51, 
pp. 253-273 (1939). 

Holmberg, Erik. On the clustering tendencies 
among the nebulae. Astrophys. Jour., vol. 
92, pp. 200-234 ( r 94°); Mt. W. Contr., 
No. 633. 

Hubble, Edwin. Barred spirals. Read at Berke- 
ley meeting, A. A. S. (1939); (abstract) 
Pubs. A. A. S., vol. 9, pp. 249-250 (1939). 

The motion of the galactic system 

among the nebulae. Jour. Franklin Inst., 
vol. 228, pp. 131-142 (1939). 

The nature of the nebulae. Annual 



Report Smithsonian Inst., 1938, pp. 137-148. 
Huffer, C. M. See Stebbins, Joel. 
Humason, Milton L. The new aluminum cOat 

of the 100-inch reflector at Mount Wilson. 

Pubs. A. S. P., vol. 52, pp. 145-146 (1940). 
and R. Minkowski. A supernova in 

NGC 5907. Pubs. A. S. P., vol. 52, pp. 145- 

147 (1940). 
Joy, Alfred H. The award of the Bruce Gold 

Medal to Frederick Hanley Seares. Pubs. 

A. S. P., vol. 52, pp. 69-79 (1940). 



MOUNT WILSON OBSERVATORY 



25 



Joy, Alfred H. The motions and dimensions of 
our stellar system. A. S. P. Leaflet, No. 132. 

7 PP- (i94o). 

See Adams, Walter S. 

King, Robert B., and Donald C. Stockbarger. 
Absolute /-values by the method of total 
absorption. Astrophys. Jour., vol. 91, pp 
488-502 (1939); Mt. W. Contr., No. 629 

Absolute f-values of Cd 1 and 

Cu 1 lines. Read at Seattle meeting, Amer 
Phys. Soc. (1940); (abstract) Phys. Rev. 
vol. 58, p. 187 (1940). 

Merrill, Paul W. Pressure shifts of lines of TVi 
Astrophys. Jour., vol. 89, pp. 321-322 (1939) 

Notes on bands in the visual region of 

the spectra of long-period variable stars 
Pubs. A. S. P., vol. 51, pp. 356-357 (1939) 

Celestial shadows. A. S. P. Leaflet, No 

133. 8 pp. (1940). 

Peculiarities of the lines Ha and D3 

in stellar spectra of class cA. Read at Berke- 
ley meeting, A. A. S. (1939) ; (abstract) Pubs. 
A. A. S., vol. 9, p. 267 (1939). 

Spectra of long-period variable stars. 

107 pp. Chicago, Univ. Chicago Press (1940) . 

and Roscoe F. Sanford. Peculiarities of 



line displacements in the spectrum of 48 
Librae (HD 142983). Read at Seattle meet- 
ing, A. S. P. (1940); (abstract) Pubs. A. S. 
P., vol. 52, p. 279 (1940). 
Minkowski, R. Spectra of the supernova in 
NGC 4725. Pubs. A. S. P., vol. 52, pp. 206- 
207 (1940). 

See Humason, Milton L. 

Moore, Charlotte E. See Russell, Henry 

Norris. 
Mulders, Elizabeth Sternberg. See Nicholson, 

Seth B. 
Nicholson, Seth B. The great magnetic storm 

of March 24, 1940. Read at Seattle meeting, 

A. S. P. (1940); Pubs. A. S. P., vol. 52, pp. 

169-171 (1940). 

Discovery of the tenth and eleventh 

satellites of Jupiter and observations of 
these and other satellites. Astron. Jour., 
vol. 48, pp. 129-132 (1939). 

and Elizabeth Sternberg Mulders. 

Sunspot activity during 1939. Pubs. A. S. P., 
vol. 52, pp. 32-33 (1940). 

Provisional solar and magnetic 

character-figures, Mount Wilson Observa- 
tory, April, 1939 — March, 1940. Terr. Mag., 
vol. 44, pp. 484-487 (1939); vol. 45, pp. 
104-106, 218-220 (1940). 

and Myrtle L. Richmond. Positions of 



Jupiter's satellites. Astron. Jour., vol. 49, 
pp. 9-1 1 (1940). 
Pettit, Edison. Spectral energy-curve of the sun 
in the ultraviolet. Astrophys. Jour., vol. 91, 
pp. 159-185 (1940) ; Mt. W. Contr., No. 622. 



— Radiation measurements on the eclipsed 
moon. Astrophys. Jour., vol. 91, pp. 408—420 
(1940); Mt. W. Contr., No. 627. 

The temperature of a prominence. 

Pubs. A. S. P., vol. 51, pp. 289-291 (1939). 

— Limb-darkening on the sun. Read at 
Palo Alto meeting, A. S. P. (1939); Pubs. 
A. S. P., vol. 51, pp. 321-327 (1939). 

— The possible escape of prominences from 
the sun. Read at Seattle meeting, A. S. P. 
(1940); Pubs. A. S. P., vol. 52, pp. 172-181 
(1940). 

— A mechanical improvement in the spec- 
trohelioscope. Pubs. A. S. P., vol. 52, pp. 
292-293 (1940). 

Solar prominences. A. S. P. Leaflet, 



No. 137. 8 pp. (1940) 
Porter, R. W. See Anderson, John A. 
Randers, Gunnar. A note on the evolution of 

extragalactic nebulae. Astrophys. Jour., vol. 

92, pp. 235-246 (1940); Mt. W. Contr., 

No. 634. 
Richardson, Robert S. The nature of solar 

hydrogen vortices. Read at Seattle meeting. 

A. S. P. (1940); (abstract) Pubs. A. S. P 

vol. 52, p. 282 (1940). 
— Sunshine and its effects. A. S. P. Leaflet 

No. 135. 6 pp. (1940). 
Richmond, Myrtle L. See Nicholson, Seth B 
Sanford, Roscoe F. Nova Monocerotis 1939 

Pubs. A. S. P., vol. 52, pp. 35-37 (1940). 
Carbon isotope bands in stars of spectral 

class R. Pubs. A. S. P., vol. 52, pp. 203—205 

(1940). 

Interstellar gases. A. S. P. Leaflet, No. 



130. 7 pp. (1939). 
— See Merrill, Paul W. 



Seares, Frederick H. The dust of space. Pubs. 
A. S. P., vol. 52, pp. 80-115 ( I 94 )- 

Spitzer, Lyman, Jr. Spectra of M supergiant 
stars. Astrophys. Jour., vol. 90, pp. 494-540 
(1939); Mt. W. Contr., No. 619. 

Stebbins, Joel. The electrical photometry of 
stars. Read at the Symposium on the Photo- 
electric Cell in Astrophysical Research, 
Seattle meeting, A. S. P. (1940); Pubs. A. S. 
P., vol. 52, pp. 235-243 (1940). 

C. M. Huffer, and A. E. Whitford. 

The colors of 1332 B stars. Astrophys. Jour., 
vol. 91, pp. 20-50 (1940); Mt. W. Contr., 
No. 621. 

The mean coefficient of 



selective absorption in the galaxy. Astrophys. 

Jour., vol. 92, pp. 193-199 (1940); Mt. W. 

Contr., No. 632. 
Stockbarger, Donald C. See King, Robert B. 
Stromberg, Gustaf. Soul of the universe. 

244 pp. Philadelphia, McKay (1940). 



26 



CARNEGIE INSTITUTION OF WASHINGTON 



Summary of Mount Wilson magnetic observa- 
tions of sunspots July, 1939 — June, 1940. 
Pubs. A. S. P., vol. 51, pp. 298-301, 361-364 
(1939); vol. 52, pp. 42-45, 148-151, 209-211, 
295-298 (1940). 

van Maanen, Adriaan. The photographic de- 
termination of stellar parallaxes with the 
60- and 100-inch reflectors. Seventeenth 
series. Astrophys. Jour., vol. 91, pp. 503-505 
(1940); Mt. W. Contr., No. 630. 

The parallax of Mayall's star of large 

proper motion. Pubs. A. S. P., vol. 51, p. 291 

(i939)- . 

Preliminary parallaxes of Luyten 789-6 

and Wolf 424. Pubs. A. S. P., vol. 51, 

P- 358 (i939)- 

Stars with photographic absolute mag- 
nitude fainter than +15. Read at Berkeley 
meeting, A. A. S. (1939); (abstract) Pubs. 
A. A. S., vol. 9, p. 265 (1939). 

Sterren met photographische absolute 



helderheden beneden i5 I ? 1 o. Hemel en 
Dampkring, vol. 37, pp. 434-436 (i939)- 

Whitford, A. E. See Stebbins, Joel. 

Wilson, O. C. Possible applications of super- 
novae to the study of the nebular red shifts. 
Astrophys. Jour., vol. 90, pp. 634-636 
( r 939)- 



— Relative populations of 2 X S and 2 3 S 
states of helium in the Orion nebula. Astro- 
phys. Jour., vol. 91, pp. 360-362 (1940); 
Mt. W. Contr., No. 625. 

— The Wolf-Rayet spectroscopic binary 
HD 193576. Astrophys. Jour., vol. 91, pp. 
379-393 (1940); Mt. W. Contr., No. 623. 

— Physical characteristics of the Wolf- 
Rayet stars. Astrophys. Jour., vol. 91, pp. 
394-407 (1940) ; Mt. W. Contr., No. 624. 

Velocities and intensities of absorption 



lines produced by helium in the Orion 
nebula. Read at Berkeley meeting, A. A. S. 
( x 939); (abstract) Pubs. A. A. S., vol. 9, 
pp. 274-275 (1939). 
Wilson, Ralph E. The mean absolute magni- 
tude of class R stars. Astrophys. Jour., vol. 
90, pp. 486-493 (1939); Mt. W. Contr., 
No. 618. 

Galactic rotation and absorption. Astro- 
phys. Jour., vol. 92, pp. 170-192 (1940); 
Mt. W. Contr., No. 631. 

The General Catalogue of stellar posi- 
tions and proper motions. A. S. P. Leaflet, 
No. 128. 8 pp. (1939). 

The masses of the stars, by H. N. Russell 

and C. E. Moore (review). Pop. Astron., 
vol. 48, pp. 285-286 (1940). 



SPECIAL PROJECTS: ASTRONOMY 



S. A. Mitchell, University of Virginia. Astronomical studies at the Leander McCormic\ 
Observatory. 



In addition to the funds from the Carnegie 
Corporation of New York made available 
through the Carnegie Institution of Wash- 
ington, referred to in Year Book No. 38, for 
the erection of a 10-inch Cooke camera, small 
grants have been made by the Corporation 
to support research activities undertaken 
with the 10-inch and also with the 26-inch 
refractor. 

The research work of the Leander Mc- 
Cormick Observatory is centered around the 
latter instrument, at one time the largest 
telescope in existence. Although it is a visual 
refractor, practically all the work is done by 
photography. The chief interest is in posi- 
tional astronomy. During 1940, volume 8 of 
the "Publications," consisting of 750 pages, 
has been distributed. The volume is entitled 
The trigonometric parallaxes of 650 stars, and 
contains also a discussion of 1350 parallaxes 
determined at the Leander McCormick 
Observatory. 

In spite of the great advances of recent 
years in the determination of stellar distances 
by spectroscopic and other methods, the 
trigonometric parallaxes are the only ones 
directly observed, and all other stellar dis- 
tances must be calibrated or standardized by 
the trigonometric values. In The masses of 
the stars (p. 60, 1940), by H. N. Russell and 
C. E. Moore, there appears the statement: 
"For the giants, however, there is a very 
serious difference between the mean reduced 
trigonometric and spectroscopic parallaxes. 
This arises from the parallaxes themselves." 
In order to make more certain the informa- 
tion from the trigonometric parallaxes, at the 
request of Dr. Adams of the Mount Wilson 
Observatory, the McCormick Observatory has 
put on its observing program about 70 giants 
of late spectral types. Up to date, the Mc- 
Cormick Observatory has completed the 
trigonometric parallaxes of 570 stars of K 
and M types. 

27 



Proper motions of high accuracy are de- 
rived at the McCormick Observatory by com- 
paring measurements from early and late 
photographs taken with the 26-inch refractor. 
This proper-motion work yields mean paral- 
laxes of groups of stars whose distances are 
too great to be measured by the annual paral- 
lactic displacements. Groups under investi- 
gation include: (1) stars of each magnitude 
from 8th to 12th in various galactic latitudes, 
(2) 10th- and nth-magnitude stars grouped 
according to spectral class and galactic lati- 
tude, (3) stars in dark and in bright portions 
of the Milky Way, (4) Cepheid variables, 
and (5) long-period variables. Mean distances 
may be obtained from proper motions by two 
independent methods: we may compare their 
average peculiar motion with the known aver- 
age space velocities of brighter stars, or we 
may compare the apparent drift ,of the group 
as a whole with the sun's velocity which 
occasions this drift. This second method 
yields, in addition to the mean distances, the 
position of the apex of the solar motion with 
respect to each group. 

Likewise, this proper-motion work yields 
such valuable items as the constants of the 
precessional motion of the earth's pole around 
the pole of the ecliptic, together with a deter- 
mination of the constants characterizing the 
rotation of the galaxy. The proper-motion 
work further gives a determination of the 
constants of the velocity ellipsoids of various 
groups of stars, and also gives information 
on the concentration of various types of stars 
toward the galactic plane. 

In 1937, in McCormick Observatory "Publi- 
cations," volume 7, there was a discussion of 
18,000 proper motions distributed in 341 
regions of the sky. A second investigation of 
the same type is now in progress in order to 
give additional information and to clear up 
some doubtful points. The second publication 
will include 12,000 additional faint stars in 



28 



CARNEGIE INSTITUTION OF WASHINGTON 



440 regions of the sky. As of June 30, 1940, 
the motions of 10,000 of these stars in 368 
regions have been measured. The experience 
gained from volume 7 has caused certain 
modifications in the procedure, with the re- 
sult that stars fainter than the 12th magnitude 
and within 1 cm. of the edge of the plate are 
not measured. As a result of the omission of 
these faint stars with greater accidental errors 
of measurement, the stars of the second 
proper-motion investigation will have fewer 
stars per region but a relatively higher weight. 

In the first investigation there were a total 
of 5200 stars with known spectra, but in the 
second investigation there will be 7500 stars 
with spectra. Up to the present, 5500 stars 
of the second investigation have been assigned 
spectral types. 

In 1926, the Mount Wilson and the McCor- 
mick Observatories inaugurated a cooperative 
research on the Cepheid variables in order to 
determine the zero point and scale of the 
period-luminosity law. The plan called for 
proper motions to be determined by photo- 
graphs with the 60-inch Mount Wilson re- 
flector and independently with the 26-inch 
McCormick refractor, and also for radial 
velocities to be determined at Mount Wilson. 

To insure the highest accuracy in the radial 



velocities it was unnecessary for a time in- 
terval to elapse as in the proper-motion work, 
and accordingly the line-of-sight motions have 
already been published by Joy. For the 
Cepheid problem a higher accuracy is re- 
quired than for the other McCormick proper- 
motion investigation, with the result that two 
pairs of plates, each with two images, are 
being measured instead of one pair. The 
McCormick measures now proceeding show 
a satisfactorily high accuracy represented by 
an internal probable error of o'/oo22 in the 
annual motions. The reference frames of 
stars are chosen after inspection of the spectral 
plates. Where possible, 20 stars of early types 
and of 10th or nth magnitude are selected. 
As the photographs are measured both in 
right ascension and in declination coordinates, 
the amount of measurement involved in the 
McCormick method of determining the 
proper motion of one Cepheid variable is 
considerably greater in amount than the 
measurement required for one trigonometric 
parallax. 

BIBLIOGRAPHY 

Mitchell, S. A., D. Reuyl, and others. The 
trigonometric parallaxes of 650 stars. Publi- 
cations of the Leander McCormick Observa- 
tory, vol. 8. 750 pp. (1940). 



The ultimate goal of the science of geology 
is a complete description of the distribution 
of terrestrial matter in time and space. When 
we go beyond the descriptive stages of this 
science and seek a fundamental basis for an 
understanding of the complex processes that 
have given to the Earth its present gross and 
detailed structures and even now are remold- 
ing its surface and convulsing its interior, we 
find ourselves in the domains of physics and 
chemistry. Indeed, we get into the difficult 
and undeveloped regions of these sciences 
where it is necessary to examine the behavior 
of recalcitrant substances under conditions of 
temperature and pressure that strain to the 
limit the possibilities of laboratory technique. 
The development of this physicochemical 
aspect of geology has been the objective of 
the Geophysical Laboratory since its founda- 
tion. The Laboratory is, therefore, one unit 
operating in the ever advancing front line 
of the sciences of physics, chemistry, and 
geology, and as such it attains its highest use- 
fulness when its activities combine judiciously 
a long-range systematic attack on the refrac- 
tory problems in its field with an alertness to 
recognize and an adaptability to take advan- 
tage of recent advances in other sectors of the 
front and, in return, to use its own peculiar 
resources, both tangible and intangible, to 
open up new fields for exploitation by 
workers in neighboring sectors. Although 
such considerations pertain in a greater or less 
degree to all scientific research, they are pecu- 
liarly applicable to the program of the Geo- 
physical Laboratory on account of the broad 
scope of its problems. The adherence to these 
general principles may perhaps be illustrated 
by the following outline of some of the results 
obtained during the past year. Because the 
attitude of a modern research laboratory is 
really more akin to that of a division in an 
army actively engaged in operations over a 
wide front than to the ruminative and lei- 



GEOPHYSICAL LABORATORY 

Washington, District of Columbia 

L. H. ADAMS, Director 

surely outlook so often associated with tradi- 
tional scholasticism, it will be convenient, in 
the delineation of these results, to borrow cer- 
tain military phrases of well-known connota- 
tion in order to emphasize the relation of the 
various investigations to the Laboratory's 
general objectives. 

Siege problems. It has long been recog- 
nized that organizations devoted to pure re- 
search can render a distinct contribution to 
the general advance of science by undertaking 
siege problems, that is to say, strategic and 
sometimes formidable problems whose subju- 
gation requires the long-continued applica- 
tion of specialized techniques, generally with 
the compilation and interpretation of copious 
data. Such operations may not always yield 
newsworthy results, but they represent con- 
solidated advances into rich regions which 
not only are valuable in themselves but also 
afford bases for theoretical and industrial 
advances in other directions. 

The Laboratory's chief activity of this type 
has been the investigation of the genesis of 
rock-forming minerals by a systematic study 
of the temperatures at which synthetic 
minerals are in equilibrium with molten mix- 
tures of known composition. The results are 
systematized according to phase rule methods 
and are presented as equilibrium diagrams, 
from which the complete course of crystalliza- 
tion of mixtures of a given set of substances, 
commonly called a system, may be deduced. 

The past year has seen the successful 
occupation of two extensive portions of this 
front by the completion of the two funda- 
mental oxide systems, potash — alumina — 
silica (K..O — A1 2 3 — Si0 2 ) and soda — alu- 
mina — silica (Na 2 — AL0 3 — SiO a ). These 
results have a direct bearing on the formation 
of the geologically important minerals leucite, 
potash-feldspar, albite, and nepheline, and 
show the course of crystallization of these 
minerals when excesses of their component 



29 



30 



CARNEGIE INSTITUTION OF WASHINGTON 



oxides are present in the molten mixtures. 
Because of the complexity of the natural 
magmas and the variability in composition of 
natural minerals, studies on these funda- 
mental systems are more directly applicable 
to mineral formation than are equilibrium 
diagrams of systems whose components are 
compounds of ideal mineral compositions. A 
knowledge of the chemical behavior of these 
two systems is essential in an attack on the 
problems of the latest stages in the crystalliza- 
tion of igneous rocks on account of their rela- 
tion to the system \aliophilite — nepheline — 
silica (KAlSi0 4 — NaAlSi0 4 — Si0 2 ), the 
"residua" system of petrology, and because 
they give the fundamental basis from which 
to launch an attack on hydrous systems that 
bear directly on pegmatite formation and the 
hydrothermal alteration of minerals. 

Several other anhydrous systems involving 
rock-forming minerals have been completed 
during this year. One of these is the system 
ferrous oxide — alumina — silica (FeO — A1 2 3 
— Si0 2 ), which not only is of considerable 
geological interest because of the information 
it gives concerning the crystallization of the 
minerals olivine, hercynite, mullite, and 
corundum, but also is immediately applicable 
to various metallurgical processes and to the 
production of refractories and other ceramic 
materials. 

Another "siege" problem in the Labora- 
tory's program depends for its basis of attack 
on the advances made in the work to which 
reference has been made. This problem con- 
cerns the effect of water on the crystallization 
of minerals from melts consisting of alkalis, 
alkaline earths, alumina, and silica. It is now 
well established that after a molten magma 
has deposited the greater proportion of its 
crystalline minerals it is relatively rich in vola- 
tile materials, of which water is the most 
abundant. The presence of these volatile 
materials modifies the course of the crystal- 
lization that would be expected from a study 
of the anhydrous melts. Moreover, the water 
and other volatiles, on escaping from the 
magma, may, by their transport of heat and 
chemical activity, produce extensive altera- 
tions in the colder surrounding rock and, by 



their mobility, lead to the segregation of eco- 
nomically valuable materials as ore deposits. 
The strategic importance of such a problem 
is evident, and justifies continuing effort de- 
spite the difficulties that arise from the neces- 
sity for combining a high-temperature with a 
high-pressure technique and for overcoming 
the corrosive action of the volatile constitu- 
ents. Among the results obtained during the 
year, one of special significance was obtained 
during the investigation of the action of water 
under a pressure of 200 atmospheres on 
molten mixtures of soda, lime, and silica. 
Under these conditions the field of chemical 
composition in which the compound devitrite 
(Na 2 • 3CaO • 6Si0 2 ) is stable is consider- 
ably reduced, by the extension of the fields 
of stability of silica, on the one hand, and of 
the metasilicate Na 2 • 2CaO • 3Si0 2 , on the 
other. Because of the analogous (but not 
identical) chemical structures of devitrite and 
feldspars and of the metasilicate and a basalt, 
a study of the effect of water on this com- 
pound has a direct bearing on the possibilities 
of similar effects during the formation of 
natural rocks. 

Reconnaissance problems. Present-day igne- 
ous activity, as seen in the volcanic and hot- 
spring areas of the world, occupies a promi- 
nent place in the Laboratory's program, partly 
because of the importance of understanding 
and predicting volcanic activity, and partly 
because of the conviction that what is happen- 
ing in volcanic areas today is closely related 
to what happened in the past when the rocks 
of the Earth's crust were solidifying. Al- 
though significant progress has been made in 
these studies, it should be noted that the work 
is still in the stage of "reconnaissance." Field 
studies of active volcanoes or hot-spring 
regions by geologists, and especially by investi- 
gators having an appreciation of the scope 
and limitations of laboratory experimental 
methods, for the purpose of locating strategic 
problems and planning methods of attack are 
operations of prime importance in this field. 
During the past year an expedition from the 
Laboratory, in cooperation with the Depart- 
ment of Terrestrial Magnetism, visited vol- 
canic areas in Guatemala and succeeded in 



GEOPHYSICAL LABORATORY 



31 



getting into closer touch with some of the 
very active centers than has been possible in 
the past. A new group of hitherto inaccessible 
fumaroles was reached, the chemical activity 
examined, temperatures measured, and speci- 
mens for laboratory study collected. It was 
found possible to study at close range the 
extrusion of lava from Santiaguito, the active 
region of the volcano Santa Maria, observe 
the temperatures, and obtain an improved 
conception of the nature of the lava. 

Of recent years many instruments have 
been developed for making observations from 
which inferences concerning subterranean 
conditions may be drawn; it is a priori highly 
probable that these techniques will yield 
valuable information concerning volcanic 
regions. In the course of the cooperative 
studies a start was made on the determi- 
nation of gravity at significant locations in 
Guatemala, a series of electrical resistivity 
measurements over large pumice deposits 
were made, observations of Earth tremors 
with portable seismometers were carried out 
in the vicinity of volcanoes, and the use of 
buried microphones as practiced by F. A. 
Perret in Martinique was tested in the region 
near Santa Maria. A great part of the data of 
these observations has not yet been analyzed, 
but one important piece of progress made by 
the expedition was a partial bridging of the 
wide and unpredictable gap between the de- 
velopment of instruments and their use under 
the unfavorable conditions encountered in 
volcanic regions. 

Expeditionary problems. The combination 
of reconnaissance work with systematic 
studies gives a self-contained type of investi- 
gation that has its analogue in the military 
expedition. This is illustrated by the work on 
the radioactivity of sediments on the ocean 
floor. By means of an apparatus developed in 
the Laboratory, it is now possible to collect, 
from almost any depth in the ocean, core 
samples of the sediments between six and ten 
feet long in which the vertical distribution of 
sediment in the natural deposit is preserved. 
As previously reported, a number of these 
samples have been collected in the Atlantic 
Ocean and Caribbean Sea. 



With the aid of a semiautomatic apparatus 
developed for the purpose, rapid and precise 
measurements of the radium content of 
samples taken systematically from different 
parts of the cores of sediment have been 
made. The results form a typical example of 
the value of systematic measurements. In 
three cores, taken from regions of low lati- 
tude, it was found that the radium content at 
the top of the sample (latest sediment) was 
high as compared with the average for igne- 
ous rocks, and that it increased rapidly with 
depth for a short distance, passed through a 
maximum, and finally decreased until the 
bottom of the core (earliest deposits) was 
reached. This result, which has never been 
predicted, could not have been obtained with- 
out the availability of long core samples, 
numerous measurements, and sensitive meth- 
ods of radium determination. Its implications 
are that these sediments are so young that 
the radioactive equilibrium has not been 
reached in them, and that in the later deposits 
ionium is present in excess while uranium is 
deficient. If radioactive equilibrium has not 
been attained, it is possible to measure the 
degree of attainment at any depth within the 
sediment and thence to calculate from the 
known properties of the radioactive elements 
the time that has elapsed since the sample was 
deposited. This opens up a method of deter- 
mining not only the age but also the rate of 
deposition (the distribution in space and 
time) of these sediments covering the vast 
areas of the ocean floor. The value of these 
deductions is enhanced by the development 
of a method whereby their validity may be 
tested experimentally; and work is now in 
progress on this phase of the problem. The 
heat generated by radioactive elements in the 
Earth's crust is an important factor in the 
thermal history of the Earth, and it may be 
noted that from this point of view the results 
emerging from the systematic studies give a 
different and presumably better picture than 
did results from measurements on isolated 
and fortuitous samples taken by other devices. 

Development and proving of experimental 
and theoretical equipment. As we leave the 
surface of the Earth and go into its interior. 



32 



CARNEGIE INSTITUTION OF WASHINGTON 



we find that the pressure rises very rapidly. 
Even in the depths of the ocean it reaches the 
relatively large value of iooo atmospheres, and 
at the center of the Earth it has the enormous 
magnitude of 3,000,000 atmospheres. An 
understanding of the physics and chemistry 
of matter under high pressures is, therefore, 
a prime requisite for any "deliberate specula- 
tions" (to quote Robert Boyle) on the nature 
of the Earth's interior. Although this subject 
has considerable theoretical interest, the 
specialized technique involved and the lack 
of industrial stimulus has made it one of the 
least developed branches of physics and chem- 
istry, and even now less than half a dozen 
laboratories in the world devote much atten- 
tion to work with high pressures. In this 
phase of its work, therefore, more than in any 
other at present, the Laboratory is forced to 
forge its own theoretical and experimental 
artillery, and the past year has seen several 
noteworthy developments. One theoretical 
aspect of the work has been concerned with 
the development of a foundation for under- 
standing the phenomena of flow and fracture 
in solids. In particular, the observation made 
at Harvard University that the strengths of 
solids increase rapidly when they are confined 
under hydrostatic pressures exceeding 10,000 
atmospheres has been placed on a theoretical 
basis. 

These theoretical results have been applied 
to the design and construction of an apparatus 
whereby the range of experimental observa- 
tions under high pressure is enormously ex- 
tended, a project in which the Department 
of Terrestrial Magnetism cooperated. The 
apparatus consists essentially of one pressure 
generator inside another. In the outer gener- 
ator a pressure of some 17,000 atmospheres is 
produced and maintained while a carboloy 
piston is forced into the inner vessel, where a 
pressure as high as 200,000 atmospheres has 
been produced. It is of importance to relate 
that the apparatus is large enough to insure 
the possibility of making precise measure- 
ments of the behavior of matter under these 
pressures, which correspond to a depth of 
approximately 300 miles below the surface of 
the Earth. 



Significant progress toward another objec- 
tive in high-pressure physics has been made 
this year through the combination of the 
Laboratory's high-pressure resources and its 
knowledge of minerals with the technique of 
sensitive magnetic measurements developed 
by the Department of Terrestrial Magnetism. 
The origin of the major portion of the Earth's 
magnetic field is an old but completely un- 
solved problem. Before a satisfactory answer 
can be given, we must know whether it is 
possible or highly improbable that the mag- 
netic field is due to the presence in the Earth 
of a ferromagnetic substance. It is important, 
therefore, to discover whether any elements 
or compounds of sufficient abundance geo- 
logically are ferromagnetic under the high 
temperatures and pressures which exist 
within the Earth. Generally speaking, in- 
crease of temperature above a certain point 
destroys the ferromagnetism of substances; 
the problem is therefore to determine if the 
rise of pressure is large enough to annul the 
effect of rise of temperature. Results obtained 
this year show that the temperature at which 
a spinel of the composition CdFe 2 4 - 
MgFe 2 4 loses its ferromagnetism is raised 
about half a degree for each 1000 atmospheres 
increase in pressure. This result, although 
obtained at low temperatures, is a noteworthy 
step toward a solution of the problem. It 
shows that rise of pressure does offset the 
effect of rise of temperature in certain sub- 
stances at least, and that the magnitude of 
the pressure effect is large enough to be 
significant. 

Flanging operations. An understanding of 
the effect of pressure on physicochemical 
properties such as chemical reactivity, solu- 
bility, acidity, and alkalinity in systems of 
geological interest is also an important objec- 
tive of the Laboratory. It is expedient to 
divide the attack on this problem into two 
phases: first, an investigation of the general 
principles governing the effect of pressure on 
chemical behavior in any type of system (i.e. a 
mixture of two or more reacting components) 
by a study of relatively tractable systems; and, 
second, an investigation of the specific factors 



GEOPHYSICAL LABORATORY 



33 



which characterize each system of geological 
interest with a view to applying the results 
emerging from the first phase. An essential 
part of the first phase, namely, molecular 
interaction in liquid solutions under different 
conditions of temperature and pressure, is 
being actively studied at the Laboratory. 
New results have given us a clearer notion of 
the nature of solutions and have opened up 
undeveloped fields in physical chemistry for 
exploitation by other workers. 

The solutions whose behavior are of chief 
interest to the Laboratory are silicate melts at 
high pressures and aqueous solutions both at 
low temperatures in the depths of the ocean 
and at high temperatures in hot springs and 
in ore-depositing fluids. The phenomena en- 
countered in these solutions are among the 
most complicated in all physical chemistry, 
a circumstance which is due in part to the 
peculiar spatial distribution of the molecules 
in these liquids. In the development of a 
general basis for the study of the effects of 
pressure and temperature on these solutions, 
the contributions of the various molecular 
interactions to the observable phenomena 
must be differentiated and evaluated. During 
the past year two promising methods of at- 
tacking this problem have been followed. The 
behavior of some solutions was examined 
under changes of pressure and temperature 
so combined that the volume remained con- 
stant. Under these conditions the long-range 
forces between the molecules are presumed to 
be constant and the observed changes are 
attributed to changes in the short-range 



forces, including changes in molecular distri- 
bution. The second method involves the use 
of model solutions to estimate the importance 
of the different factors. The study of solu- 
tions of salts dissolved in glycol has thrown 
considerable light on the effects of changes of 
molecular distribution on the properties of 
water solutions. 

The field of pressure chemistry is still so 
little explored that a search for qualitatively 
new phenomena is profitable. An examina- 
tion of the effects of pressure and temperature 
on the absorption of light by some solutions 
has revealed a new effect whose further study 
leads to interesting speculations about the 
connection between the weak intermolecular 
actions that cause solutions to depart from 
ideal behavior and the strong interactions that 
lead to profound chemical changes. 

Intercommunication. The military analogy 
applies also to the applications of techniques 
acquired in other fields of knowledge to the 
problems of Earth science. An interesting 
example is furnished by the recent results on 
the fluorine content of rocks and ocean- 
bottom samples. An easy and surprisingly 
accurate method for the determination of 
fluorine, developed recently at the University 
of Michigan, was applied to rock analysis at 
the Laboratory. The result was unexpected 
and of considerable significance in that it 
showed that fluorine is not a minor con- 
stituent of rocks, as was formerly supposed, 
but is commensurate in importance with 
chlorine both in terrestrial rocks and in ocean- 
bottom sediments. 



HIGH-TEMPERATURE STUDIES OF ANHYDROUS SYSTEMS AND THEIR 
PRESENTATION BY EQUILIBRIUM DIAGRAMS 



Silicates 

Systems involving the combination of early- 
crystallizing and late-crystallizing minerals. 
The course of crystallization of a mixture of 
silicates and oxides having a complexity ap- 
proaching that of a natural magma has not 
yet been amenable to laboratory study, and 
it is highly probable that a long time will 
elapse before any results of practical or theo- 
retical value can emerge from such an investi- 
6 



gation. From the study of suitably chosen 
systems, however, conclusions of such general 
validity may be drawn that their application 
to natural magmas seems justifiable. Among 
advantageous systems for intensive study are 
those that deposit the minerals presumed to 
crystallize early in the history of a natural 
magma, and also the minerals of much lower 
melting points that have appeared at the last 
stages of magmatic differentiation. An impor- 



34 



CARNEGIE INSTITUTION OF WASHINGTON 



tant part of these studies consists in determin- 
ing how the residual liquids vary in com- 
position as the crystallization of different 
ternary and quaternary mixtures proceeds. 
Studies of the systems leucite — diopside — 
silica (KAl(Si0 3 ) 2 — CaMg(Si0 3 ) 2 — Si0 2 ) 
and nepheline — jayalite — silica (NaAlSi0 4 — 
Fe 2 Si0 4 — Si0 2 ) are completed and pub- 
lished [Schairer, Bowen]. Experimental work 
on the system leucite — anorthite — silica 
(KAl(SiO s ) 2 — CaAl 2 Si 2 8 — Si0 2 ) was fin- 
ished during the past year and is being pre- 
pared for publication. A portion of the 
system nepheline — diopside — silica has been 
investigated. This is not a ternary system. 
Work on the system nepheline — anorthite — 
silica [Schairer, Crocker], which has been in 
progress since 1937, may be divided into 
two parts: the study of the system albite — 
anorthite — silica (NaAlSi 3 O s — CaAl 2 Si 2 O s — 
Si0 2 ), which is nearly completed; and the 
study of the system nepheline — albite — silica, 
which is still in a preliminary stage. 

In all these, and also other systems, the 
residual liquids become richer and richer in 
the alkali-alumina silicates as the crystalliza- 
tion proceeds. Except for such modification 
as may be caused by the presence of water 
and other volatile materials, this result shows 
that the key to an understanding of the late 
stages in the crystallization of natural magmas 
lies in the alkali-alumina silicate systems. 

Alkali-alumina silicates [Schairer, Bowen]. 
In addition to the completion of the work on 
the potash — alumina — silica and soda — alu- 
mina — silica systems mentioned in the intro- 
ductory part of this report, further progress 
has been made on the system \aliophilite — 
nepheline — silica ( KAlSi0 4 — NaAlSi0 4 — 
Si0 2 ). The complexity of the various phe- 
nomena encountered in this system and the 
length of time required for the attainment 
of equilibrium (approximately one month 
for each run in the feldspar field) makes the 
work very slow, but the results appear to 
justify the effort. During this year the prepa- 
ration of homogeneous mixtures of the proper 
compositions for determining the limits of 
ternary hexagonal solid solutions of kaliophi- 
lite, nepheline, and albite has been completed. 



As a part of our systematic attack on the 
chemistry of the alkali silicates, a paper on 
the system Na 2 Si0 3 — Li 2 Si0 3 — Si0 2 has been 
published, and the work on the system 
K 2 Si 2 5 — Na 2 Sio0 5 has been completed 
[Kracek]. 

Quaternary systems. For a long time the 
system lime — magnesia — alumina — silica has 
been of special interest to both the geologist 
and the technologist. Many important rock- 
forming minerals appear in this system, and 
numerous binary and ternary combinations 
of these four oxides have been studied system- 
atically at the Laboratory during the past 
thirty years. In the general attack on the 
complete quaternary system [Schairer, Os- 
born], which is now being prosecuted vigor- 
ously, the previous work on many binary 
mixtures of lime, alumina, magnesia, and 
silica has been checked, generally with excel- 
lent agreement; but in some cases need for 
revision has been revealed, for example 
in the system akermanite — wollastonite 
(Ca 2 MgSi 2 7 — CaSi0 3 ). The subsidiary ter- 
nary system gehlenite — akermanite — wollas- 
tonite (Ca 2 Al 2 SiO ? — Ca 2 MgSi 2 7 — CaSi0 3 ), 
which combines simple members of the melli- 
lite and pyroxene groups, has also been in- 
vestigated and the results of experiments on 
the melting relations are ready for publica- 
tion. Complete data have been obtained for 
the liquidus and for the three-phase bound- 
aries, which determine the compositions of 
the solid solutions and the courses of crystal- 
lization of all ternary liquids, either with 
perfect equilibrium or with perfect fraction- 
ation. There is no ternary eutectic, but there 
is a ternary minimum with three phases 
coexisting in equilibrium, a liquid, a solid 
pyroxene (CaSi0 3 ), and a mellilite (a solid 
solution of gehlenite and akermanite). At 
temperatures well below the liquidus, indeed 
below 1325 ° C, pure akermanite breaks up 
into two unidentified solids. This phenome- 
non, together with the behavior of the solid 
solutions, is being investigated further. A 
study of melting relations in another subsidi- 
ary system, wollastonite — diopside — anorthite 
(CaSi0 3 — CaMg(Si0 3 ) 2 — CaAl 2 Si 2 8 ), is al- 
most finished. 



GEOPHYSICAL LABORATORY 



35 



The problem of the formation of the 
augites, which are among the commonest of 
the rock-forming pyroxenes, requires for its 
solution a knowledge of the behavior of mix- 
tures containing alumina in varying amounts. 
The temperature — composition relations in 
the quaternary system lime — ferrous oxide — 
alumina — silica should shed light on the role 
of alumina in the augites. In the study of 
this system, which promises to be a long and 
complicated matter, a substantial start has 
been made by the completion of the plane 
ferrous oxide — anorthite — silica, a plane in 
which the important minerals silica, anorthite, 
hercynite, olivine, and wiistite appear. Ex- 
periments on two other subsidiary planes, 
ferrous oxide — anorthite — alumina and fer- 
rous oxide — anorthite — wollastonite , are also 
well under way. 

The system sodium oxide — boric oxide — 
silica (Na 2 — B 2 3 — Si0 2 )- Boric oxide is 
known to accumulate in significant amounts 
during the course of crystallization of a 
natural magma, and it may have a consider- 
able effect in insuring that magmatic solu- 
tions are at all times below their critical 
temperatures. Furthermore, the volatility of 
boric oxide in steam makes it potentially 
important as an agent in the formation of ore 
deposits by transport through the vapor phase. 
The experimental work necessary for an 
understanding of this system is practically 
finished [Morey, Ingerson]. By an investiga- 
tion of the compositions varying linearly be- 
tween sodium orthoborate and sodium ortho- 
silicate and between sodium metaborate and 
sodium metasilicate, especially in melts con- 
taining only a small percentage of boric oxide, 
it was established that the fields of stability 
of sodium orthosilicate and sodium meta- 
silicate are contiguous. This upholds Kracek's 
conclusion that no compound intermediate in 
composition between sodium metasilicate and 
sodium orthosilicate (Na 2 SiO a and Na 4 Si0 4 ) 
exists, in spite of the contentions of workers 
in other laboratories that there is a stable 
compound of the formula 3Na 2 • 2Si0 2 . 

In the binary system Na 2 — B 2 3 , Morey 
and Merwin found, besides the orthoborate, 
a metaborate (Na 2 ■ B 2 3 ), a diborate 



(Na 2 ■ 2B 2 3 ), a triborate (Na 2 • 3B 2 3 ), 
and a tetraborate (Na 2 • 4B 2 3 ). Each 
of these has a field in the ternary system, but 
the field of the metaborate dominates the 
system. It extends across the diborate — disili- 
cate join, and comes in contact with the field 
of quartz at the quintuple point quartz — 
sodium disilicate — sodium metaborate — liquid 
— vapor, at a boric oxide content of about 
20 per cent. The field of quartz is thus adja- 
cent to the fields of sodium disilicate; also 
probably to the fields of each of the borates 
in succession, and finally to the field of 
crystalline boric oxide. 

In the region adjacent to the quartz bound- 
ary (on the liquidus surface) and centered 
roughly in a trough less than 10 per cent in 
width, at the composition of about 25 per cent 
Na 2 and 20 to 50 per cent B 2 3 , melts have 
hot been induced to crystallize, because the 
liquidus temperatures are so low. Mixtures 
poorer in sodium oxide crystallize with less 
difficulty until compositions very close to zero 
Na 2 are reached; even melts containing only 
3 per cent Na 2 have been crystallized, and 
no difficulty was encountered with mixtures 
on the line joining silica to sodium tetra- 
borate. By extrapolation of the results for 
mixtures containing only small amounts of 
Na 2 it is hoped that information concerning 
the melting relations in the binary system 
B 2 3 — Si0 2 may be deduced. Such an extra- 
polation under less favorable conditions was 
made in the system CaO — B 2 O a — Si0 2 , and 
a check is very desirable. 

Telluride Minerals 

The discovery of important quantities of 
gold in the form of the mineral calaverite or 
its weathering products in the enormous 
heaps of discarded waste at Cripple Creek 
and Camp Bird Mine, Colorado, revived in- 
terest in the little-known gold and silver tellu- 
ride minerals calaverite (Au(Ag)Te 2 ), kren- 
nerite (Au(Ag)Te 2 ), sylvanite (AuAgTe 4 ), 
petzite (AuAg 3 Te 2 ), and hessite (Ag 2 Te). 
From the chemical and crystallographic as 
well as the geological standpoints, these 
minerals present features of such interest as 



36 



CARNEGIE INSTITUTION OF WASHINGTON 



to warrant considerable study. Attention has 
been given to the crystal structures of these 
minerals, which are of an unusual character 
[Tunell], and the investigation of the tem- 
perature — composition relations in the system 
tellurium — silver — gold was finished during 
the past year [Kracek, Ksanda]. Only two 
ternary compounds, corresponding to sylvan- 
ite and petzite, were found. Both decom- 
pose on melting, the former giving AuTe 2 
and a liquid, the latter giving a gold — silver 
alloy and a liquid. There is a single ternary 
eutectic at approximately 330 ° C with the 
solids Te, Ag 3 Te 2 , and AuAgTe 4 and a 
liquid of the approximate atomic ratio 35 Ag: 
4Au:6iTe coexisting at equilibrium. A very 
large portion of this equilibrium diagram is 
occupied by the liquidus surface of the gold — 
silver alloy. Liquid immiscibility between 
AgoTe and Ag extends slightly into the 
ternary system, and none of the possible sec- 
tions through the ternary system is a binary 
system. Copper, silver, and gold all belong to 
the same group in the periodic table, as do 
also sulfur, selenium, and tellurium. One 
would expect, therefore, that certain general 
similarities might be found in the various 
systems composed of these metals and non- 
metals. Such similarities are found in the 
systems of copper or silver (denoted by M) 
with sulfur, selenium, or tellurium (denoted 
by X), but the systems involving gold are 
exceptional. For example, highly stable 
compounds of the formula M- 2 X are well 
known, but the sulfides and selenides of gold 
are very unstable, and the only telluride of 
gold, AuTe 2 , melts at a low temperature. 



Moreover, in all six of the M — X systems 
there is a region of liquid immiscibility be- 
tween M 2 X and M, whereas AuTe 2 and Au 
merely give a eutectoid relation in the com- 
plete melting diagram. Gold and silver 
alloys form a complete series of solid solu- 
tions, but gold and silver tellurides do not 
enter into solid solution to any marked extent. 

Copper and Iron Sulfides 

Work on the sulfides of iron and copper, 
which has an important bearing on the for- 
mation of ore deposits, is being continued 
[Merwin, Greig]. The extremely compli- 
cated chemistry of these systems and the 
exacting technique required for microscopic 
examination make progress rather slow. Dur- 
ing this year Einar Jensen, from the Uni- 
versity of Oslo, Norway, has been cooperating 
with Merwin and Greig in studying melting 
relations and transformations above 600 ° C 
in the sulfides of iron and copper that contain 
low amounts of sulfur, especially mixtures of 
FeS (pyrrhotite) and Cu 2 S (chalcocite). In 
these mixtures much solid solution is known 
to exist, and, although good results have been 
obtained for the freezing-point curves, the 
effects of solid solution at lower temperatures 
are still obscure. Both the quenching method 
and the thermal analysis method have been 
used in this work. It is necessary to enclose 
the charges of the sulfides in specially de- 
signed silica-glass containers. Breakage of 
these vessels, owing to low-temperature trans- 
formations in the charges, and adherence of 
the melts to the glass are some of the prin- 
cipal experimental difficulties. 



EQUILIBRIUM IN SYSTEMS CONTAINING WATER AT VARIOUS 
PRESSURES AND TEMPERATURES 



Silicate Systems 

The system water — sodium oxide — silica 
(FLO — Na 2 — Si0 2 ) has been studied under 
a pressure of 200 atm. of steam over a range 
of compositions extending to mixtures 
slightly richer in silica than the sodium 
disilicate (Na 2 Si0 5 ) — quartz (Si0 2 ) eutectic 
[Morey, Ingerson]. The saturation curve at 



this pressure runs parallel to the liquidus 
curve in the anhydrous system, being lower 
by 1 75 C at the composition Na 2 Si0 3 and 
by 165 ° C at the composition Na 2 Si0 5 . The 
composition of the eutectic is thus displaced 
in the direction of higher silica content. 

The low-temperature region of the system 
water — sodium oxide — lime — silica (FLO — 



GEOPHYSICAL LABORATORY 



37 



Na 2 — CaO — Si0 2 ), which includes the 
ternary eutectic sodium disilicate — devitrite 
(Na 2 • 3CaO • 6Si0 2 ) — quartz and the field 
of stability of devitrite, has been studied also 
under a pressure of 200 atm. of steam. The 
field of devitrite is invaded on one side by 
quartz and on the other by the metasilicate 
(Na 2 • 2CaO • 3Si0 2 ), with the result that 
an unexpected raising of the melting point in 
a large portion of this region is apparently 
produced by the presence of the water. In the 
regions of composition where devitrite is still 
stable, the melting point is lowered by the 
water, as would be anticipated. In the studies 
of the system water — sodium disilicate — al- 
bite, the 200-atm. isobar is more than half 
completed. 

The results just mentioned have to do 
primarily with the lowering of the melting 
points of certain silicates by the water that 
they dissolve when in contact with steam 
under high pressure. It is of great importance 
to find out just how much water is dissolved 
by the silicate melts under these conditions; 
in order to do this, the charge is quenched 
from a temperature just above the crystalliz- 
ing point. Some results have been obtained, 
but an unexpected and still unexplained diffi- 
culty has been encountered in that the charges 
lose water during the quenching and are 
blown up into a mass resembling a pumice. 
Apparently this effect is not due to known 
or obvious causes, and it is being further 
investigated, not only with a view to its elimi- 
nation, but also because of its significant 
implications in volcanism. 

Systems Containing Alkali Hydroxides 
and Carbonates 

By means of a filter autoclave in which the 
solubilities of corrosive materials may be 
measured at elevated temperatures and 
atmospheric pressure [Morey, Burlew], the 
solubility of sodium hydroxide (NaOH) in 
solutions containing some carbonate has been 
measured over that part of the system in 
which NaOH is a solid phase. An average 
accuracy of 1 in 2000 was realized. It was 
found that at temperatures below about 



ioo° C the field of NaOH is very narrow, 
whereas at higher temperatures it broadens 
rapidly. This change can be expressed in 
terms of the position of the curve of double 
saturation that represents the boundary be- 
tween the fields of NaOH and of Na 2 CO s . 
Along this curve the ratio of CO, to Na 2 
is a simple exponential function of the tem- 
perature. By extrapolation of this curve of 
double saturation, the binary eutectic between 
NaOH and Na 2 C0 3 has been found to lie 
at a temperature of 287^90 and a composi- 
tion of 81.70 per cent NaOH and 18.30 
per cent Na 2 C0 3 . Along any isotherm 
across the field of NaOH, which gives the 
solubility of NaOH at that temperature in 
solutions containing different amounts of 
Na 2 C0 3 , the total Na 2 content shows only 
slight variation; therefore extrapolation of 
these isotherms to the limiting binary system 
NaOH — H 2 can be performed with little 
loss of accuracy. This extrapolation gives 
values for the solubility of NaOH in pure 
water at intervals of 30 from 60 to 300 C. 
They lie on a parabola of slight curvature. 
During the year gratifying progress was 
made on the construction of a filter autoclave 
in which solubilities may be measured at 
elevated temperatures under fairly high pres- 
sures [Burlew]. The successful construction 
of such a piece of apparatus is essential to 
the prosecution of the program of work on 
the effect of water on crystallization of 
minerals, the immediate specific problem 
being an investigation of the behavior of the 
system H 2 0— Na 2 0— K 2 0— A1 2 3 — Si0 2 , 
between 150 and 500 ° C, an extension of the 
investigation described in the previous para- 
graph. The construction of the apparatus has 
reached the stage at which preliminary tests 
can be carried out, and it has been found that 
the stirrer can be operated successfully at 
500 C, under a steam pressure of 200 atm., 
the upper limits set in the original plans. 
This and other tests have shown that the 
design of the apparatus is sound, but before 
it can be used for routine determinations of 
solubility, a number of refinements and cali- 
brations need to be made. 



38 



CARNEGIE INSTITUTION OF WASHINGTON 



Solutions at Low Temperatures and 
High Pressures 

During the past year the major portion of 
the work in this field [Gibson, Loeffler] has 
been devoted to an analysis of the pressure — 
volume — temperature data for a series of solu- 
tions of salts in water according to the 
methods suggested by the previous studies on 
pure liquids. Ancillary studies included the 
measurement of pressure — volume — temper- 
ature relations for the pure liquids carbon 
tetrachloride, from 25 to 65 ° C, and ethylene 
glycol, from 25 to 105 , and for a series of 
solutions of sodium bromide in glycol from 
25 to 105 , all over the pressure range 1 to 
1000 atm. The thermal expansibilities, the 
compressibilities, the pressure — temperature 
coefficients, the energy — volume coefficients, 
and related thermodynamic quantities of all 
the liquids, the glycol solutions, and the aque- 
ous solutions including water were computed 
at all temperatures and pressures in the ex- 
perimental range. The results are summa- 
rized as follows. 

Carbon tetrachloride. This liquid, whose 
molecules have spherical symmetry, was 
studied with a view to establishing the be- 
havior of normal liquids under changes of 
pressure and temperature. The energy — 
volume coefficient decreases slightly (5 per 
cent over 40 ) when the temperature is 
raised at constant volume, and the attractive 
internal pressure varies inversely as the cube 
of the volume, an observation of theoretical 
interest. 

Water. It is well known that the molecular 
distribution in liquid water makes it almost 
unique among liquids and is such that each 
molecule has on an average only 4 or 5 
nearest neighbors, whereas in most liquids a 
molecule has 10 to 12 such neighbors. This 
distribution arises from directed forces be- 
tween water molecules, and its rapid change 
with temperature is reflected in many of the 
unusual physical properties of water. The 
energy — volume coefficient of water shows up 
the anomalous properties of this liquid in a 
striking way, because instead of decreasing 
slightly with temperature at constant volume, 
as in carbon tetrachloride, it increases more 
than 300 per cent in the range 25 to 85 ° C. 



This effect is directly connected with the 
changes in molecular distribution in water, 
and, although it diminishes as the tempera- 
ture is raised, it is large enough at 100° to 
indicate that water is still quite abnormal at 
its boiling point. A rough extrapolation 
shows that changes in molecular distribution 
become of minor importance between 150 
and 200 . 

Ethylene glycol. This liquid is an excellent 
solvent for salts. Glycol solutions have been 
used as models in the study of water solu- 
tions, on the assumption that the peculiarities 
arising from changes in molecular distribu- 
tion in water are negligible in glycol, al- 
though glycol and water solutions are quite 
similar in other respects. The new results 
justify this assumption by showing that the 
energy — volume coefficient of glycol increases 
only slightly when the temperature is raised 
from 25 to 105 C at constant volume, the in- 
crease being less than 10 per cent as great as 
that observed in water. This result indicates 
that glycol shares to a minor extent the pecu- 
liarities of water and that the method used 
to calculate the attractive internal pressure of 
normal liquids breaks down when applied 
to glycol. 

Solutions of sodium bromide in ethylene 
glycol. Before one can make any significant 
generalizations concerning the relation of the 
volume changes on mixing to the known 
properties of substances dissolved in water, 
one must know the relative contributions of 
the volume changes due to changes in the 
molecular distribution in the water (produced 
by the salt) and of the volume changes due to 
the better-known forces between the water 
and the dissolved molecules. On the assump- 
tion that changes in molecular distribution 
contribute only a small part of the volume 
changes on mixing in glycol solutions, four 
solutions of sodium bromide in glycol wefe 
examined with a view to a comparison of 
their behavior with that of solutions of the 
same salt in water. At a given temperature 
the energy — volume coefficients of these solu- 
tions increase somewhat as the concentration 
of salt rises. For a given solution the energy — 
volume coefficient changes very little with 
temperature at constant volume. Other sig- 



GEOPHYSICAL LABORATORY 



39 



nificant observations may be described in 
terms of the "apparent volumes" of the salt in 
these solutions, the apparent volume being de- 
fined as the volume which the salt appears to 
have in the solution on the assumption that 
the volume of the solvent remains unchanged 
by the process of mixing, and the apparent 
expansibilities, which are defined mutatis 
mutandis in the same way. The apparent 
volumes of sodium bromide in glycol increase 
with pressure and concentration, but decrease 
with temperature at constant pressure. The 
most significant result, however, is that the 
apparent volume of the salt remains essen- 
tially constant when the temperature rises at 
constant volume, indicating that in a solution 
where disturbing changes in molecular distri- 
bution are negligible, the apparent volume of 
the salt depends only on the total volume of 
the solution, that is, on the mean distance of 
separation of the molecules. 

Aqueous solutions. Computations with the 
data for solutions of sodium chloride, sodium 
bromide, and lithium bromide in water over 
the whole range of concentrations gave the 
following results. The energy — volume coeffi- 
cients of the individual solutions resemble 
those of water in that they increase greatly 
with temperature at constant volume. In- 
crease of concentration of salt, however, 
increases the magnitude of the energy — 
volume coefficients at a given temperature 
and, moreover, diminishes the temperature 
variation of the energy — volume coefficients 
at constant volume. In other words, addition 
of salt to the water produces the same quali- 
tative effects as raising its temperature. 

At or near room temperature, the apparent 
volumes of salts dissolved in water increase 
with temperature; the apparent thermal ex- 
pansibilities are positive and, moreover, de- 
crease as the concentration of the solution 
rises. In this respect the behavior of salts 
dissolved in water differs from that of salts 
dissolved in any other solvent. All these 
anomalies disappear at higher temperatures, 
the apparent volumes of the salts passing 
through maxima around 50 ° C as the tem- 
perature is raised at constant pressure. 

One feature of these investigations deserves 
emphasis, namely, the valuable information 



given by an analysis of the effect of tempera- 
ture at constant volume. As one more ex- 
ample, we may note that the apparent vol- 
umes of sodium chloride and sodium bromide 
in water continue to increase when the tem- 
perature is raised at constant volume, the 
maxima noticed on the constant-pressure 
curves having disappeared. When the total 
volume is kept constant, the presumption is 
strong that the long-range forces between the 
ions of the salt and the water molecules are 
also constant. The increase in apparent vol- 
ume with temperature under such conditions 
brings out clearly its dependence on the 
molecular distribution in the liquid (water), 
in striking contrast with the behavior of salts 
in glycol under similar circumstances. Fur- 
thermore, a comparison of the apparent- 
volume-temperature curves at constant total 
volume for sodium chloride and sodium bro- 
mide furnished conclusive evidence that the 
main difference between these two salts dis- 
solved in water lay in the relative attractions 
of the chloride and bromide ions for water 
molecules, and not in their effects on the 
molecular distribution. 

Another interesting feature of the results 
is that they indicate that at temperatures be- 
tween 180 and 200 C the thermodynamic 
properties of water solutions certainly become 
much simpler than at room temperature. All 
this work points to a continuously increas- 
ing similarity between salt solutions in water 
and in glycol (the model solution) as the 
temperature rises. This fact encourages us 
to believe that fairly simple theoretical con- 
siderations may give results of useful accuracy 
for dilute aqueous solutions at higher temper- 
atures. The importance of a knowledge of 
the behavior of dilute aqueous solutions at 
these temperatures and at high pressures in 
the study of ore-depositing solutions, or of 
volcanological phenomena, makes it desirable 
to extend the pressure — volume — temperature 
studies into this region at an early date. 

Solubility of Calcium Sulfate in 
Sea Water 

Measurements of the relative solubilities of 
gypsum and anhydrite in aqueous solutions 
of sea salts at 30 ° C are now completed 



4 o 



CARNEGIE INSTITUTION OF WASHINGTON 



[Posnjak], and the results have been pub- 
lished. With increasing concentration of sea 
salts the solubilities of gypsum and of anhy- 
drite at first increase rapidly, then pass 
through maxima, and finally decrease gradu- 
ally. This decrease is more rapid for anhy- 
drite, and at 4.8 times the normal salinity of 
sea water anhydrite becomes the stable phase. 
Sea water is unsaturated with respect to 



gypsum and anhydrite, and the foregoing 
results show that on evaporation most of the 
calcium sulfate in sea water will be deposited 
as gypsum. It is probable, therefore, that 
sedimentary deposits of anhydrite were laid 
down at temperatures above the transition 
point of these minerals or were formed from 
gypsum after it had been deposited from 
marine solutions. 



RADIOACTIVE ELEMENTS IN ROCKS AND IN SEDIMENTS 
FROM THE OCEAN FLOOR 



It is now well established that a knowledge 
of the relative amounts of various radioactive 
elements in different rocks and of the total 
amount and distribution of radioactive ele- 
ments in the Earth's crust is of prime impor- 
tance in a study of the ages of rocks and 
minerals and in the problem of the thermal 
history of the Earth. Though much attention 
has been given to the securing of the neces- 
sary data, it must be emphasized that our 
information in this field is far from complete. 
It has been shown that radioactive elements 
are distributed throughout all the materials 
of the Earth's crust, the largest concentration 
being found in granites and the least in sedi- 
mentary rocks, but little systematic work has 
been done. In particular, the vast areas of 
the Earth that lie under the ocean have 
hardly been studied at all, and such results 
as have been obtained are of doubtful signifi- 
cance. With the core-sampling gun developed 
by Piggot it is possible, not only to extend by 
several hundred per cent the area from which 
samples may be taken, but to obtain from 
any place on the ocean floor a core several 
feet long in which the vertical and horizontal 
distribution of radioactive elements in the 
ocean-bottom sediments may be studied. 

Determinations of radium in cores from 
the bottom of the Atlantic and Pacific oceans 
formed the main part of this year's work 
[Piggot, Urry]. Four cores from low lati- 
tudes were examined, three from the Bartlett 
Trough (between Cuba and Jamaica) and a 
red-clay core taken by the Scripps Institution 
of Oceanography at a point 220 miles west- 
southwest of San Diego, California. The 



radium content was determined at nine or 
more points in each core. At the surface the 
amount of radium in each core is larger than 
the average found in igneous rocks, a result 
which agrees with previous fragmentary data. 
The radium content increases with depth for 
some distance until it passes through a maxi- 
mum, and thereafter decreases steadily. The 
same general type of distribution was found 
in all four cores. It should be mentioned that 
the initial increase of radium content with 
depth is very rapid and that consequently the 
observed radium content of specimens ob- 
tained with the older "snapper sampler" 
depends to a large extent on the accidental 
depth to which the snapper penetrated the 
sediment. In the introductory paragraphs 
reference has already been made to the impli- 
cations of this newly found radium distri- 
bution in depth. 

Cores taken from the foot of the slope on 
the continental shelf off the Grand Banks, at 
a position approximately midway between the 
Grand Banks and the Mid-Atlantic Ridge, 
were also examined, the radium content being 
determined at ten or more places in the core. 
The radium-content curves obtained for these 
cores have the same general shapes as those 
just described, but a somewhat erratic distri- 
bution of radium in the cold-water zones of 
these cores has been noted. 

As a result of these measurements it now 
seems certain that radioactive equilibrium is 
not attained in any of the cores or in sea 
water itself. Accordingly, information of 
great interest about the age and rate of 
deposition of the sediments is to be expected 



GEOPHYSICAL LABORATORY 



41 



if the amounts of the individual elements 
uranium, radium, and ionium can be meas- 
ured. To accomplish this, an alpha-particle 
counter has been built and calibrated in terms 
of the Laboratory's standard radium solution. 
It has been established that uranium, radium, 
and ionium may be separated from each other 
by a simple chemical procedure involving 
co-precipitation, and that the alpha-particle 
counter may be used to determine the amount 
of each element. A determination of uranium 
and ionium in a Finnish granite — a rock of 
adequate age for the existence of the equi- 



librium relation between uranium or ionium 
and the previously measured radium — indi- 
cates that the method is satisfactory. 

The newly built apparatus by which the 
radium content of rocks and core samples is 
determined in a semiautomatic and routine 
way was used in all the work on the core 
samples, after being checked by samples 
whose radium content had been determined 
by other methods. In addition, the radium 
contents of twenty-two samples of rocks re- 
ceived from the National Bureau of Stand- 
ards were measured with the new apparatus. 



PHYSICAL PROPERTIES OF ROCKS AND MINERALS 



Determination of Crystal Structures 
by X-Ray Diffraction 

The study of the structures of the gold- 
silver-telluride minerals sylvanite, krennerite, 
and calaverite has been continued during the 
past year and is now nearing completion. 
Because of the unusual nature of the struc- 
tures that were proposed as a result of studies 
of the relative intensities of the scattered 
rays, it was considered desirable to apply the 
most powerful methods available to confirm 
them. Four Patterson and Fourier series 
were computed, and although the work was 
laborious, up to 200,000 terms being com- 
puted in a single series, it was greatly facili- 
tated by the use of an improved set of strips 
and stencils together with a sorting board. 
The segregation of the odd and even terms 
with the new stencils reduces the labor to less 
than half that formerly required. A new and 
excellent equator Weissenberg photograph of 
sylvanite was made, the cause of the unsatis- 
factory nature of previous ones having been 
detected and eliminated. The results of these 
calculations confirm the structures and the 
values of the parameters previously proposed. 
Contour maps of the electron density distri- 
bution in the unit cells as projected on various 
planes have been prepared from the results of 
the Fourier analysis [Tunell]. 

Heat of Melting of Albite 

In order to control the speculations made 
about the alteration of rocks by igneous and 



other activity, to place on a quantitative basis 
generalizations about the thermal processes in 
the Earth, and to provide the data necessary 
for thermodynamic calculations, it is essential 
that data on the heats of melting and of trans- 
formation of minerals and on their specific 
heats be obtained with as high precision as 
possible. An apparatus satisfactory for this 
purpose has been built and tested [Roberts]. 
The determination of the heat of melting of 
the important mineral albite presents some 
difficulties. It is nearly impossible to obtain 
adequate amounts of completely crystalline 
pure synthetic albite or to estimate with suffi- 
cient precision the fraction of crystalline solid 
in a partially crystallized sample. On the 
other hand, the natural product, although 
well crystallized, is known to contain trouble- 
some impurities. Direct measurements gave 
an average of 77 calories per gram for the 
heat of melting of two samples of natural 
albite containing 2 per cent anorthite and 
1 per cent orthoclase. Many years ago Bowen 
calculated the heat of melting of albite from 
the melting curves in the system albite — 
anorthite and gave the value 48.5 calories per 
gram. Some of the assumptions involved in 
the calculation may be open to question, but 
the divergence of the two results is difficult 
to explain. Another method of attack, how- 
ever, presented itself. Studies of the system 
sodium oxide — alumina — silica in the Labora- 
tory have shown that albite and sodium 
disilicate form a simple binary system with 



4 2 



CARNEGIE INSTITUTION OF WASHINGTON 



a eutectic at 765 ° C and that mixtures in this 
system crystallize very readily and completely 
even when they contain as much as 80 per 
cent albite. This observation offered an ade- 
quate source of crystalline albite mixed with 
a known amount of additional material, and 
on the assumption that the heat of mixing 
of liquid albite with liquid sodium disilicate 
is negligibly small, the latent heat of melting 
of albite was computed from the observed 
heat of melting (at 780 °) of an albite-disili- 
cate mixture (50 weight per cent of each) 
and the known heat of melting of sodium 
disilicate. This result was 40 calories per 
gram for the heat of melting of albite. The 
discrepancy among these three figures illus- 
trates the difficulty of determining latent heats 
of substances like silicates, and indicates that 
further study on other mixtures containing 
albite is necessary. 

Magnetic and X-Ray Diffraction Studies 
of Sulfide Minerals 

An investigation is under way on the solid 
solution series of sulfur in ferrous sulfide 
[Posnjakj, a series which includes the 
mineral pyrrhotite. These solutions comprise 
a small field which extends to not much over 
4 per cent of extra sulfur. Only those ma- 
terials in the sulfur-rich half of the series are 
ferromagnetic. In spite of numerous investi- 
gations of these solid solutions, some of which 
are very recent, many statements regarding 
the character of the phases appearing in the 
series and their behavior are in need of veri- 
fication. The thermal study carried out in 
this Laboratory a few years ago did not 
clarify all aspects of the problem. Accord- 
ingly, further attempts to solve it were made 
by means of magnetic measurements. The 



results obtained to date indicate quite clearly 
that the Curie temperature of the ferromag- 
netic members of the series rises appreciably 
with an increasing sulfur content. However, 
the absence of ferromagnetism in the part of 
the series with the lower sulfur content can- 
not be ascribed to a lowering of the Curie 
temperature below room temperature, but 
appears to depend on some fundamental 
change in properties with composition. 
X-ray examinations indicate that three dif- 
ferent phases may be distinguished in the 
series of solid solutions between room tem- 
perature and 350° C. The differences in the 
diffraction patterns of these phases are small, 
however, and require much further study. A 
very considerable difficulty in the study of 
these solid solutions lies in the sluggishness 
with which transitions of phases take place. 

Determination of Volatile Materials in 
Rocks and Minerals 

Although the exploratory phase of this 
work is now completed, the subject is by no 
means exhausted, and indeed the significance 
of the nature and exact amounts of volatile 
materials in rocks and in sublimates or incrus- 
tations from volcanic regions is just being 
realized. Volatile materials play an important 
role in the propagation of heat and chemical 
reactions throughout rocks, and the traces 
they leave behind give important data for 
inferences. In order to facilitate the routine 
and precise analysis of gases in rocks, an 
apparatus embodying the latest improvements 
in vacuum technique and design is being 
constructed [Shepherd]. This apparatus is 
simpler than the older one formerly used in 
the Laboratory, but is more powerful and 
versatile. 



EXPLORATORY AND COOPERATIVE STUDIES 



Geophysical and Geological Explorations 
in the Volcanic Regions of Guatemala 

The investigations of present-day igneous 
activity, in which the Department of Terres- 
trial Magnetism is cooperating with the 
Laboratory, were continued during the past 



year by another expedition to Guatemala 
[Zies, Wright, Rooney, Green, Adams]. In 
the plan of this work two primary objectives 
have been set up: (1) the focusing of all the 
resources of newly developed instruments and 
technique on the exploration of atmospheric, 



GEOPHYSICAL LABORATORY 



43 



surface, and subterranean phenomena in and 
around this region where so many forms of 
volcanic activity are concentrated; and (2) 
close observation of the physical and chemical 
aspects of volcanic activity in the field, with 
a view to devising significant laboratory ex- 
periments which may provide the basis for 
an understanding of the natural phenomena 
and may supply a clue for disentangling their 
many complexities. Needless to say, the con- 
clusions of such laboratory studies should be 
continuously rechecked in the field. It must, 
of course, be emphasized that both these 
objectives can be attained only after explora- 
tions have been made and the problem of 
reaching the areas of most interest has been 
solved — a problem whose simplicity is more 
apparent than real. 

Gravity measurements. The Pacific slopes 
and the highlands of Guatemala are covered, 
often to a great depth, with pumiceous de- 
posits of a very low density. Although the 
absence of topographic maps and precise geo- 
logical information concerning this area 
makes interpretation difficult, it seemed de- 
sirable to make a few tests of the use of 
gravity determinations — a priori a very 
promising method — for estimating the thick- 
ness of the layers of pumice and for apprais- 
ing the applicability of this method to general 
problems of volcanism. Two Brown gravity 
pendulum instruments and accessory equip- 
ment, kindly loaned by the U. S. Coast and 
Geodetic Survey, were taken on the expedi- 
tion, and stations were occupied at the 
National Observatory in Guatemala City and 
near the Western Observatory (Observatorio 
del Occidente) in Quezaltenango [Wright]. 
The auxiliary electrical circuits in the instru- 
ments gave trouble from mutual interference 
and from interference with a near-by radio 
transmitter, but these difficulties were over- 
come, satisfactory measurements were secured, 
and some valuable experience in the operation 
of these instruments under exacting service 
conditions was obtained. 

Measurements of earth resistivity. The 
character of the pumiceous deposits in the 
plain around the city of Quezaltenango indi- 
cates a relatively recent origin, and suggests 



that the pumice originated from local sources. 
To determine the depth of this material, meas- 
urements of the electrical resistance of the 
ground mass were made at a number of sta- 
tions arranged in a grid [Rooney, Green]. 
The results show that there is no pronounced 
change for a depth of more than 1000 feet 
in the central portion of the mass. Earth- 
resistance measurements on the plain around 
Guatemala City indicate that the pumice is 
probably of different origin from that around 
Quezaltenango. 

Magnetic observations. The survey of 1939 
showed that measurements of the vertical in- 
tensity of the Earth's magnetic field gave 
valuable information about the depth or ex- 
tent of masses of hot igneous material under- 
lying the volcano Santa Maria. Similar hot 
masses are believed to underlie the plain of 
Quezaltenango, and for this reason magnetic 
measurements at points in this vicinity were 
carried out [Green]. In addition, a number 
of the former stations were reoccupied. The 
analysis of these results has not yet been 
completed. 

Atmospheric ionization. An apparatus for 
counting separately the a and (3 radiation in 
the atmosphere was provided by the Depart- 
ment of Terrestrial Magnetism. After pre- 
liminary trials at low altitudes, it was set up 
at the main camp at an elevation of 7000 feet 
near the crater floor of the volcano Santa 
Maria. Later, a trail was cut through the 
vegetation on one of the ridges of the southern 
flank of the volcano, at an elevation of 10,000 
feet. This vantage point is swept by the pre- 
vailing winds carrying steam and other gases 
from the active dome, Santiaguito, which is 
on the edge of the old crater. A comparison 
of atmospheric ionization in this region and 
in one not exposed to volcanic emanation was 
attempted, but the excessive humidity soon 
rendered the apparatus inoperative. Our ex- 
perience has enabled us to suggest changes in 
the design of the electrometer which will 
render it useful under the rigorous working 
conditions in the vicinity of active volcanoes. 

Seismic observations. Two portable seis- 
mometers were mounted on posts buried 
3 feet in the ground and records were ob- 



44 



CARNEGIE INSTITUTION OF WASHINGTON 



tained at the main camp on Santa Maria and 
on the crater floor. The instruments, how- 
ever, responded only to comparatively strong 
shocks and were unaffected by the heavy 
rock slides from the shattered wall of Santa 
Maria. It was concluded that more sensitive 
seismographs will have to be employed if a 
record of the disturbances produced by the 
rather quiet extrusions of lava in this region 
is desired. 

Microphones. In his well-known work at 
Mont Pelee in Martinique, F. A. Perret has 
used buried microphones to pick up audible 
frequencies transmitted through the ground 
during volcanic activity, and he has been able 
to follow the intensity of the activity by 
noting the character of the sound in the 
phones. Mr. Perret lent us duplicates of his 
apparatus, and supplied explicit instructions 
for its use. The apparatus was set up at a 
number of stations close to the base of the 
active dome, Santiaguito. Rock slides on 
Santa Maria, some 800 feet away, were audi- 
ble in the microphones, but otherwise nothing 
but instrument noises was detectable. This 
lack of response of the microphones in this 
locality, where according to other evidence 
volcanic activity is intense, indicates that it 
is desirable at some opportune time to try out 
an instrument with higher sensitivity in cer- 
tain frequency ranges. 

Geological and geochemical results. From 
the camp site at an elevation of 10,000 feet on 
Santa Maria the complex alternation of layers 
of lava and clastic material that make up 
Santa Maria may be studied very conven- 
iently. Indeed, the processes leading to such 
formations are now visible. Constant and 
heavy erosion of the vertical walls is gradu- 
ally filling the crater with fragmental ma- 
terial. If in the near or far distant future this 
is engulfed in another great extrusion of lava, 
a volcanic breccia of the type already in place 
will be formed. 

The fumaroles on the lower eastern slope 
of Santiaguito appeared to have altered little 
during the year that had elapsed since the 
previous visit. Access was gained for the 
first time, and with much difficulty, to a 



group of fumaroles 400 feet higher up the 
slope and in line with the lower group. These 
are on a more consolidated part of the dome 
where the slope has a gradient amounting to 
from 35 to 37 . In contrast with the complete 
absence of sulfur in and around the lower 
group of fumaroles, abundant quantities of 
this element were found around the upper 
group; indeed, the sulfur seems to act as a 
cement binding the soil particles together, 
thus forming a crust that renders the ground 
impervious to steam. When the crust was 
broken, steam escaped and molten sulfur was 
observed 2 inches below the surface. The 
steam escaping from the fumaroles has a 
temperature of from 120 to 350 C, and trans- 
ports much hydrogen sulfide and sulfur. 
Many samples of incrustations and gases were 
collected for laboratory study. 

In the report for last year attention was 
called to the intermittent extrusions of hot 
lava that came from the upper part of the 
western slope of Santiaguito. This year it 
was possible to approach close enough to 
measure the temperature of the lava with an 
optical pyrometer — a difficult operation, as 
only a short time elapses between the appear- 
ance of the glowing lava and its disintegra- 
tion and fall down the steep slopes. Its tem- 
perature was found to be 725 ° C. Relying 
on experience gained last year, the expedition 
was able to reach the foot of the western slope 
of Santiaguito and establish a camp about a 
quarter of a mile from the nearest point of 
extrusion of the lava. Careful observations 
were made of the process of extrusion. It is 
not explosive; the hot mass merely swells out 
quietly and then breaks up and rolls down 
the slope. A mass roughly 9 meters in cir- 
cumference was seen to disintegrate and fall 
near one of the observation points, where its 
temperature, determined immediately with a 
thermoelectric thermometer, was found to be 
690° C. The mode of extrusion and an ex- 
amination of the cooled exudations lead to 
the conclusion that relatively fresh lava com- 
ing from within the dome engulfs and reheats 
the surrounding rock, and that when the 
resulting mass, whose temperature is now 



GEOPHYSICAL LABORATORY 



45 



quite low (700 C), comes out on a 33 ° slope 
it does not flow, but breaks up into fragments 
and rolls away. 

Surface Features of the Moon 

The activities of the Committee on Study 
of the Surface Features of the Moon have 
been continued. This is a cooperative project 
between Mount Wilson Observatory and the 
Geophysical Laboratory, begun some years 
ago in the effort to bring to bear on this prob- 
lem the combined experience and facilities 
within the Carnegie Institution. A large 
amount of observational material has been 
gathered by the committee and a portion of 
it is now being assembled for publication. 
The report on the results of visual measure- 
ments of the polarization of light from 
selected parts of the moon's surface and from 
various samples of terrestrial substances is in 
course of preparation [Wright]. Measure- 
ments of polarization by use of a photoelectric 
cell and of a quartz polarization spectrograph 
are in progress. 

The measurements of slope angles of vari- 
ous surface features of the moon, as made on 
the series of 500 lunar photographs taken 
during July 1938 at Mount Wilson Observa- 
tory, are being continued. This is a time- 
consuming task, but data are being gathered 
for a rough topographic map, with contour 
intervals of 200 meters, of the central part of 
the moon, out to 45 ° from the center of the 
lunar disk visible from the Earth. A photo- 
graphic map of the moon is also in prepara- 
tion. For this purpose photographs of the 
moon taken at the Newtonian focus of the 



100-inch telescope are transformed by a special 
photographic method, so that in each trans- 
formed negative the moon's image is pro- 
jected on the plane of mean libration and in 
the same perspective projection and scale. 

Measurements of Gravity with New 
Portable Instrument 

Work on the new model of the gravity 
meter has been continued, and the instrument 
is now being given a thorough field test in 
the vicinity of Washington. In contrast with 
previous models, the temperature of the tor- 
sion spring is maintained constant by an 
electrical thermostat; the instrument is so 
designed, however, that ice can be used for 
temperature control, if necessary. It has not 
yet been possible with the electrical thermo- 
stat to hold the temperature constant to better 
than several tenths of one degree centigrade; 
but for many measurements this degree of 
constancy appears to be adequate, especially 
as the spring is held at rest and is not under 
strain except for the 4 to 6 minutes required 
to make a measurement at a given station. 
The special features of the new model are 
proving on test to be satisfactory, and they 
enable the observer to reduce the time needed 
to occupy a station to about one-half that 
required with the preceding instrument. As 
soon as the field tests have been completed, 
the instrument will be used for a series of 
gravity measurements along selected lines in 
critical regions in which information is de- 
sired regarding the distribution of gravity 
anomalies and the degree of isostatic adjust- 
ment. 



HIGH-PRESSURE INVESTIGATIONS 



Extension of Experimental Range of 
Hydrostatic Pressure 

In connection with various problems in 
Earth science, both the Geophysical Labora- 
tory and the Department of Terrestrial Mag- 
netism have been concerned with the proper- 
ties of matter at the high pressures that are 
known to exist within the depths of the 
Earth — pressures far beyond the present ex- 



perimental range. It appears that there has 
been no satisfactory theoretical basis for 
extrapolating physical properties to these 
extreme pressures or for pushing to the limit 
the capabilities of high-pressure apparatus. 
By the joint efforts of members from the two 
departments, a careful analysis was made of 
the present status of pressure work with a 
view to canvassing the possibilities of a large 



46 



CARNEGIE INSTITUTION OF WASHINGTON 



increase in the experimental range of observa- 
tions under high pressures. There seems little 
probability of finding new varieties of metal 
that would permit a really worth-while en- 
largement of the pressure range, but, for- 
tunately, a promising line of attack is afforded 
by the remarkable increase of compressive 
strength of materials when they are subjected 
to superimposed hydrostatic pressure. 

An apparatus consisting of one small pres- 
sure generator enclosed inside another was 
designed and constructed in such a way that 
a hydrostatic pressure of approximately 18,000 
atm. could be developed in the outer vessel 
and then held constant while a carboloy piston 
was forced into the inner cylinder, thereby 
generating the high pressure. Test experi- 
ments indicated that pressures of the order 
of 200,000 atm. could be generated in the 
inner vessel [Goranson, Johnson 1, and also 
showed that the outer confining pressure in- 
creased the compressive strength of the speci- 
men of carboloy used as the piston to more 
than three times its value at atmospheric 
pressure. It is probable that the effect on the 
ultimate strength of the walls of the inner 
bomb is of even greater magnitude. The 
advantage of this two-stage "cascade" appa- 
ratus, therefore, lies not only in the circum- 
stance that the second stage immediately 
doubles the pressure range, but also in the 
great increase of strength caused by the con- 
fining pressure on the inner bomb. The pre- 
liminary experiments have shown the desira- 
bility of certain alterations in order to obtain 
better precision and control. These modifica- 
tions are now being incorporated, and investi- 
gations on auxiliary devices, such as thrust 
gauges, are being continued. 

The theory on which the construction of 
this apparatus is based has been developed in 
the past year [Goranson]. In this theoretical 
treatment the total energy of a solid is divided 
up in the usual way into a potential energy 
and a kinetic energy, and the variability of 
these quantities with respect to temperature, 
hydrostatic pressure, unidirectional stress, and 



a combination of hydrostatic pressure and uni- 
directional stress is examined. Two types of 
failure are considered: brittle rupture, which 
occurs when the potential energy increases 
above a certain value; and plastic flow, which 
is treated as a two-phase phenomenon depend- 
ing on the thermodynamic potential of the 
system, involving both the kinetic and poten- 
tial energies. Various predictions of the 
theory as to the effect of external pressure on 
the strength of materials have been verified 
and have proved useful in correlating phe- 
nomena connected with the deformation and 
flow of rocks. 

Ferromagnetic Changes under Pressure 

Because of the interest in the question as to 
the existence of ferromagnetic substances 
under the conditions prevailing in the interior 
of the Earth — a question that bears directly 
on the origin of the Earth's magnetic field — 
the work on the effect of high pressures on 
the Curie points of certain minerals has been 
continued [Goranson, Johnson, Posnjak]. 
The older pressure apparatus was modified 
so as to increase the temperature range, and 
a very sensitive reactance bridge was con- 
structed for measuring the toroid coils, whose 
inductance is of the order of 30 microhenrys. 
This bridge will detect changes of about 5 
parts per million. With this apparatus the 
permeability of the material forming the core 
of the toroid is determined at different tem- 
peratures and pressures, and the temperature 
of the Curie point, that is, the inversion from 
the ferromagnetic to a nonferromagnetic 
form, is thus found for any pressure. The 
spinel consisting of CdFe 2 4 and MgFe 2 4 
has been examined and it has been found 
that the Curie temperature of this substance 
is raised 3 C by 6000 atm. pressure. 

With a view to extending the investigations 
of the effect of pressure on the Curie tem- 
peratures to as wide a variety of substances 
as possible, plans are being made for measure- 
ments on purified gadolinium (Curie point 
around 16 C). 



GEOPHYSICAL LABORATORY 



47 



SUMMARY OF PUBLISHED WORK 



(1013) The radium content of an ocean-bottom 
core. C. S. Piggot and W. D. Urry. 
Jour. Wash. Acad. Sci., vol. 29, pp. 405- 
410 (1939). 

Determinations of the radium content of the 
surface material of the ocean bottom secured 
by the ship Carnegie, previously made by Piggot 
(Amer. Jour. Sci., vol. 25, pp. 229-238, 1933), 
revealed a surprisingly high concentration of 
this element as compared with that in the 
igneous rocks from which it must have come. 

In an effort to throw some light on the nature 
of this radium concentration in ocean-bottom 
sediments, an apparatus was previously developed 
to secure vertical cores extending some 10 feet 
below the surface of the sediment. Such cores, 
from the North Atlantic between Newfoundland 
and Ireland, proved to be very complex, but the 
one here reported is of recent "blue mud" 
throughout and fairly uniform in radium con- 
tent. This fact reflects both the uniformity of 
the material and its relatively recent deposition. 
Attention is called to the circumstance that the 
presence or absence of uranium per se could 
have no effect on the radium content of this 
core, and to the conclusion that the radium 
content is controlled very largely, especially at 
depths corresponding to a few thousand years, 
by the deposition of ionium. Why the sea 
should be deficient in radium, in relation to 
uranium, and the sediments have more than 
the equilibrium amount will probably be ex- 
plained by further studies of such cores as are 
here described. 

(1014) Phase equilibrium relations in the sys- 
tem Na 2 SiO s — Li 2 SiO s — Si0 2 . F. C. 
Kracek. Jour. Amer. Chem. Soc, vol. 
61, pp. 2863-2877 (1939). 

The phase equilibrium relations in the system 
Na 2 SiO s — Li 2 Si0 3 — Si0 2 are described in this 
paper. The work was carried out by the method 
of quenching supplemented by thermal analysis. 

There is one ternary compound, NaLiSiO s , 
which is an end member of the solid solution 
series (Na 2 ,NaLi)SiO s . It melts incongruently, 
at 847 C. At the liquidus in the system, the 
primary phases are (Na 2 ,NaLi)Si0 3 solid solu- 
tions, Li 2 SiO s , Na 2 Si 2 O g , and Li 2 Si 2 5 , all three 
of which form solid solutions of limited extent, 
and the three modifications of Si0 2 , namely, 
quartz, tridymite, and cristobalite. The liquidus 
fields meet at two ternary eutectics: one at 



697 C, with (Na 2 ,NaLi)SiO s , Li 2 SiO s , and 
Na 2 Si 2 O g , the other at 637 C, with Li 2 Si 2 5 , 
Na 2 Si 2 5 , and quartz as the eutectic constituents. 
Li 2 Si 2 O s melts incongruently throughout its 
region of existence in the system, the reaction 
temperature descending from 1033° C in the 
binary system Li 2 SiO a — Si0 2 to 641 ° C, the 
peritectic end point in the ternary system, with 
Li 2 Si 2 5 , Li 2 Si0 3 , Na 2 Si 2 5 , and liquid in co- 
existence. 

The inversion temperature of quartz and tri- 
dymite has been redetermined. The temperature 
of 870 ±io° C, given by Fenner in 1913, is 
confirmed, the value now obtained being 867 ± 

Refractive indices of glasses of various com- 
positions in the system were measured. 

A discussion of solid-solution relationships of 
sodium and lithium compounds in general is 
given, with particular reference to the theo- 
retical aspects of the subject. 

Minor revisions of the phase relations in the 
systems Na 2 SiO a — Si0 2 and Li 2 SiO s — Si0 2 , par- 
ticularly with respect to the polymorphic be- 
havior of Na 2 Si 2 5 and Li 2 Si 2 O s , are presented. 

(1015) Pressure — volume — temperature relations 
in solutions. Ill: Some thermodynamic 
properties of mixtures of aniline and 
nitrobenzene. R. E. Gibson and O. H. 
Loeffler. Jour. Amer. Chem. Soc, vol. 
61, pp. 2877-2884 (1939). 

The thermodynamic properties of mixtures of 
aniline and nitrobenzene have a twofold interest, 
first because they present an example of a series 
of solutions made from components which 
differ only slightly in their net internal pressures 
as given by the Tait equation, and secondly 
because the absorption of light by the solutions 
responds in an unexpected way to changes in 
their thermodynamic environment. The specific 
volumes at 25° C, the thermal expansions at 
io° intervals between 25 and 85°, and the com- 
pressions to various pressures up to 1000 bars at 
25, 45, 65, and 85 of six solutions of aniline in 
nitrobenzene covering the whole range of con- 
centration were measured. These data were 
represented by suitable equations from which 
the volumes, the thermal expansibilities, and 
the compressibilities could be computed at any 
pressure and temperature within the range of 
the observations. From these results it was pos- 
sible to compute the pressure — temperature co- 



4 8 



CARNEGIE INSTITUTION OF WASHINGTON 



efficients, the energy — volume coefficients, and 
the volume changes on mixing, and also to 
examine the variation of these quantities when 
the temperature was changed at constant vol- 
ume. In the light of the results of this analysis, 
a correlation was suggested between the effect 
of temperature and of mixing on the molecular 
distribution in the liquids on the one hand and 
the internal pressures and volume changes on 
mixing on the other. The attractive internal 
pressures of the solutions varied with volume 
in the same way as those of the pure com- 
ponents and could be calculated from constants 
for the pure components and the composition 
of the solution expressed in terms of a general- 
ized fraction which really introduces an em- 
pirical constant in a way that has hitherto not 
been exploited. Attempts to express the volume 
changes on mixing by the well-known "Regular 
Solution" type of equation modified by the 
introduction of the generalized fraction were 
made with moderate success. 

(1016) Identification of diamond in the Canyon 
Diablo iron. C. J. Ksanda and E. P. 
Henderson. Amer. Mineralogist, vol. 24, 
pp. 677-680 (1939). 

Small black and transparent grains embedded 
in a slice from a Canyon Diablo iron have been 
identified as diamonds by means of the X-ray 
powder spectrum method and by microscopic 
examination. The diamonds occur associated 
with some graphitic material within a troilite 
area lining the inner wall of a cavity. 

The previous identification of diamond in a 
stony meteorite is mentioned. 

(1017) Note on the fluorine content of rocks and 
ocean-bottom samples. E. S. Shepherd. 
Amer. Jour. Sci., vol. 238, pp. 1 17-128 
(1940). 

There has beeen little information about the 
amounts of fluorine present in rocks, the lack of 
data being due to the unreliable analytical 
methods available. The Willard and Winter 
procedure furnishes an easy and surprisingly 
accurate method for fluorine determination. This 
report shows that instead of being a very minor 
constituent of rocks, fluorine is present in about 
the same amount as chlorine and must be con- 
sidered in rock analyses. A tentative average 
value of about 0.04 per cent is suggested, and 
some indications point to regional concentra- 
tions. Ocean-bottom samples contain about the 
same quantities as the rock. In both rocks and 



ocean-bottom samples the fluorine varies with 
the nature of the material. 

(1018) Notes on fluorine. E. S. Shepherd. Bull, 
volcanologique. (In press; publication 
delayed because of international condi- 
tions.) 

A brief treatment of the subject matter of 
paper no. 1017, presented at the meeting of the 
International Volcanological Association held in 
Washington, D. C, in September 1939. 

(1019) Fabric criteria for distinguishing pseudo 
ripple marks from ripple marks. Earl 
Ingerson. Bull. Geol. Soc. Amer., vol. 51, 
PP- 557-570 (1940). 

Statistical grain-orientation studies of two un- 
metamorphosed ripple-marked sandstones, a 
ripple-marked quartzite, and four pseudo ripple 
marks show that a distinction between ripple 
marks and pseudo ripple marks can be made 
from fabric characteristics even when field data 
are equivocal. Some of these pseudo ripple 
marks had been previously interpreted as ripple 
marks. 

Quartz diagrams were prepared for all the 
rocks, and mica diagrams for those that con- 
tained mica. Without exception, the axes of the 
pseudo ripple marks are important fabric di- 
rections, both for mica and for quartz. In one 
case the axis of the pseudo ripple mark is 
parallel to the a fabric direction (direction of 
motion during deformation), and in two others 
it is parallel to the B fabric direction (axis of 
folding). In the fourth example of a pseudo 
ripple mark the nature of the control is not ap- 
parent. The ripple-mark axes are also principal 
fabric directions for mica, but there are important 
and easily recognizable differences between the 
arrangement in the ripple marks and that in 
pseudo ripple marks, the mica being distributed 
uniformly and symmetrically in the pseudo ripple 
marks studied, but in the actual ripple marks 
being confined to the troughs and lower parts 
of the back slopes, and thus being asymmetric 
with respect to the i'-plane. Quartz orientation 
in the ripple-marked sandstones may or may not 
be significant, but it is radically different from 
that found in the pseudo ripple marks. In the 
metamorphic pseudo ripple marks, the quartz 
axes form girdles; in the actual ripple marks, 
if there is preferred orientation of the quartz, 
the c-axes tend to lie in the bedding plane, 
more or less parallel to the axis of the ripple 
mark. 



GEOPHYSICAL LABORATORY 



49 



(1020) Physics of stressed solids. Roy W. Goran- 
son. Jour. Chem. Phys., vol. 8, pp. 323- 
334 (1940). 

The internal energy of a system is subdivided 
into a work or potential function and a thermal 
or kinetic function, the former expressed in 
terms of the current electrostatic theory of 
intercrystalline bonding, and these functions then 
examined for variations of temperature, hydro- 
static pressure, unidirectional stress, and com- 
bined hydrostatic and unidirectional pressure. 
From these considerations a theory is evolved 
which not only seems satisfactorily to explain 
and correlate phenomena of deformation, creep 
or plastic flow, cold working, elastic after-work- 
ing, rupture, shear, and certain other phenomena 
hitherto described as "anomalous" effects, but 
also has been corroborated experimentally in 
some of its predictions, in particular for the 
effect of hydrostatic pressure on deformation 
and compressive strength. The mechanism 
evolved consists of two processes, one of which 
is an elastic deformation which is a function 
of the strain or potential energy of the system. 
Failure occurs here by "brittle" rupture, wherein 
the maximum extension or maximum internal 
tension is the criterion. The other is a "deforma- 
tion by means of a two-phase transfer mechanism 
and is a function of the thermodynamic potential 
relations of the system. This latter type is also 
a function of time and therefore a function of 
the rate of application of load. When both 
processes of this mechanism are operative, failure 
occurs by shear; the criterion for this type of 
failure is given by a function of time, the strain 
or potential energy, and the thermodynamic 
potential relations of the system. Expressions are 
derived for creep or plastic flow of polycrystalline 
substances from the thermodynamic potential 
relations which not only satisfy the well-known 
phenomena of creep in metals but also express 
recent empirical creep data of some substances 
immersed in liquids in which they are some- 
what soluble. An expression is also derived 
for the "brittle" potential type of rupture under 
combined thrust and hydrostatic pressure. 

(1021) Geysir in Iceland. Tom. F. W. Barth. 
Amer. Jour. Sci., vol. 238, pp. 381-407 
(1940). 

Observations on the geology of Geysir, its 
behavior, discharge, and temperature distribu- 
tion, have led to the conclusion that the struc- 
ture of the Geysir system and the mechanism 



of its action are more complicated than was 
thought by Bunsen. 

In an appendix special consideration is given 
to Thorkelsson's assumption that a reduction in 
pressure caused by spring gases and steam as 
they rise in narrow channels is the real factor 
in geyser action. A bibliography of Geysir and 
geyser action is also appended. 

(1022) Experimental flow of rocks under con- 
ditions favoring recrystallization. David 
Griggs. Bull. Geol. Soc. Amer., vol. 51, 
pp. 1001-1022 (1940). 

"Flow" in stressed solids: an interpre- 
tation. Roy W. Goranson. Ibid., pp. 
1023-1033 (1940). 

These two papers have been combined be- 
cause of their complementary nature. The first 
one, by Griggs, presents experimentally observed 
creep or flow phenomena in rocks when sub- 
jected to certain different physical conditions of 
confining pressure, confining media, and stress. 
The second one, by Goranson, presents an in- 
terpretation of "flow" for these conditions. Ac- 
cording to the hypothesis presented here, plastic 
flow in solids takes place by means of a change- 
of-phase transfer mechanism, as solid to fluid 
to solid or solid to solution followed by re- 
crystallization of the solid. The relations derived 
constitute part of the author's more general 
treatment of stressed solids. From these con- 
siderations it is seen that the quantity labeled 
"viscosity" for solids is related to the "activation 
energy." If the hydrostatic confining pressure 
is sufficiently high, then release of the energy 
of deformation stored up in the crystal lattice 
can take place only by this change-of -phase mech- 
anism. 

(1023) Equilibrium between vapor and liquid 
phases in the system C0 2 — H 2 — K 2 — 
SiOo. George W. Morey and Michael 
Fleischer. Bull. Geol. Soc. Amer., vol. 51, 
pp. 1035-1057 (1940). 

Chemical reactions that take place by the 
agency of hot aqueous solutions and hot com- 
pressed gases, known as hydrothermal and 
pneumatolytic processes, respectively, are of pri- 
mary importance in the formation of many ore 
deposits. Concerning the mechanism of these 
processes, and especially concerning the mech- 
anism of transport of material and both the 
relative and absolute importance of transport in 
liquid and vapor phases, there is no unanimity 
of opinion. 



50 



CARNEGIE INSTITUTION OF WASHINGTON 



Field studies of ore deposits have shown that 
many ore-bearing solutions contain more than 
one volatile constituent, and numerous questions 
have been raised thereby that cannot be an- 
swered satisfactorily at present because pertinent 
physicochemical data on such systems are lacking. 
Accurate prediction of the behavior of such 
solutions can be made only after obtaining a com- 
prehensive knowledge not only of the solid — 
liquid equilibria (the solubility relations) but 
also of the effects of temperature and pressure 
on the distribution of volatiles between the liquid 
and vapor phases in multicomponent systems. 
The system here reported is the first attempt 
to obtain the latter type of data experimentally. 

The solutions concerned in ore deposition are 
extremely complex in composition, probably con- 
taining more or less of all the common rock- 
forming elements as well as a number of volatile 
constituents. It is not feasible at present to 
undertake the experimental study of such com- 
plex solutions. The number of components had 
to be reduced, to simplify the problem to a point 
where it could be handled. Accordingly, this 
work was restricted to the four-component sys- 
tem C0 2 — H 2 0— K 2 0— SiO.,. Water and carbon 
dioxide are two of the most important volatile 
constituents of magmas. Furthermore, the other 
possible choices, such as the halogen or sulfur 
compounds, would have greatly increased the 
experimental difficulties due to corrosion. K 2 
and SiO, were chosen as the other components 
because the high solubility of the potassium 
silicates in water allows working at relatively 
low pressures and because the relations in the 
bounding ternary system were known from the 
earlier work of Morey and Fenner. 

The study of the distribution of two volatiles 
between a liquid phase and a vapor phase 
requires the determination of the total amount 
and composition of each phase after equilibrium 
has been reached, or, what is equivalent and 
experimentally simpler, determination of the 
total amount and composition of one of the 
phases and knowledge of the amount and com- 
position of the original mixture. Since it is 
experimentally impracticable to sample the liquid 
phase, it is necessary to use some method for 
separating the phases and subsequently analyzing 
one or both. The method finally adopted con- 
sists in separating the phases by means of a 
valve and then analyzing the vapor phase. 

The apparatus consists essentially of two bombs 
whose inner chambers are connected through an 
opening within a valve block. One of these, 



of small free volume, contains- all the liquid 
phase plus a small known proportion of the 
vapor phase; the other, the greater part of the 
vapor phase. 

By the use of this apparatus, a study has been 
made of the equilibrium between vapor and 
liquid in the system CO.,— H 2 0— K,0— Si0 2 
at 500° C. Partial pressures of H 2 ranged up 
to 400 atm., of C0 2 , up to 25 atm., and the 
mixtures used had ratios of K 2 0:Si0 2 from 
1:1 to 1:4. 

The distribution ratios of the fraction of C0 2 
in the vapor to the ratio of the percentages of 
C0 2 to H 2 in the liquid are indicative of 
the tendency of the metasilicate melts to retain 
C0 2 and of the tendency toward expulsion of 
C0 2 with more siliceous mixtures. With drop 
in pressure at constant temperature and ratio 
K 2 0:Si0 2 , the composition of the vapor changes 
toward higher contents of C0 2 . An incidental 
study was made of the rate of solution of quartz 
in potassium carbonate solutions. 

(1024) The effects of pressure, temperature and 
chemical composition on the absorption 
of light by mixtures of aromatic amines 
and nitro compounds. R. E. Gibson 
and O. H. Loeffler. Jour. Amer. Chem. 
Soc, vol. 62, pp. 1324-1334 (1940). 

This paper gives the results of an investigation 
of a new phenomenon which was observed 
incidentally in our regular work on the thermo- 
dynamic properties of solutions under pressure. 
It was found that the absorption of visible light 
by solutions of aromatic amines in nitro or 
nitroso compounds (aniline dissolved in nitro- 
benzene being a typical example) is pushed 
very significantly toward the longer wave lengths 
when the hydrostatic pressure over the solutions 
is raised at constant temperature, and also when 
the temperature is raised at constant volume. 
When the temperature of the solutions is raised 
at constant pressure the absorption of visible 
light may increase, decrease, or remain constant; 
in any case the change is small, and it is note- 
worthy that the solutions which absorb light 
most strongly at room temperature have the 
largest negative temperature coefficients. These 
results have been correlated into a consistent 
theory which uses only ideas that are applicable 
to pure liquids, and which avoids any specific 
assumption as to the formation of colored com- 
pounds by the hypothesis that the colors of the 
solutions arise from the mutual polarizations 
of molecules when appropriate groups are in 



GEOPHYSICAL LABORATORY 



51 



close proximity, account being taken of the 
influence of pressure and temperature on the 
collision frequency, the distance of closest ap- 
proach, and the effect of short-range attractions 
between groups. In this correlation the data 
given in Laboratory paper no. 1015 (see abstract) 
were used. 

It has also been shown from orienting experi- 
ments that substituents in the nitro compound 
and in the amine influence the absorption of 
light by the solutions in a way that parallels 
closely their effects on the reducibility of the 
N0 2 or NO group on the one hand, and the 
electron mobility in the amino compound on 
the other. It is ruggested that the polarizations 
which give rise to the colors of the solutions 
may be regarded as primary steps in possible 
reactions, such as oxidation and reduction, in- 
volving transfer of electrons from the aromatic 
amine or hydrocarbon to the oxygen of the 
nitro or nitroso groups. 

(1025) Deposition of calcium sulfate from fea 
water. E. Posnjak. Amer. Jour. Sci., 
vol. 238, pp. 559-568 (1940). 

Stability relations of gypsum and anhydrite 
in solutions of sea salts are of considerable 
geological interest, as many deposits of these 
minerals are generally considered to be of 
marine origin. Since it has been shown that 
the transition point, gypsum — anhydrite, is not 
governed by a dissociation pressure relation, 
but by a four-phase equilibrium, only relative 
solubilities establish their stability either alone 
or in presence of other salts. The present de- 
terminations in solutions of sea salts were made 
at 30 C. The solubility of gypsum as well as 
that of anhydrite first increases rapidly in the 
presence of increasing amounts of sea salts, 
then goes through a maximum at about twice 
the usual salinity of sea water, and then gradu- 
ally decreases. However, the decrease is more 
rapid for anhydrite, and an intersection of the 
two curves takes place at approximately 4.8 times 
the usual salinity, the point at which anhydrite 
becomes the stable phase. 

Sea water is unsaturated with respect to 
calcium sulfate, and only after its salt content 
has increased by evaporation to 3.35 times the 
usual salinity can deposition take place. Be- 
tween this concentration and the one required 
for stable deposition of anhydrite, nearly one-half 
the total amount of calcium sulfate present in 
sea water will be deposited at 30 in the form 



of gypsum. Since at a somewhat lower tempera- 
ture, at which evaporation of a marine basin may 
be assumed to have taken place, the conditions 
in all probability will not be greatly modified, 
a large portion of calcium sulfate may always be 
expected to be deposited as gypsum. Sedimen- 
tary marine deposits of pure anhydrite must 
therefore either be at least partly derived from 
originally deposited gypsum, or have been 
formed close to or above 42 , the transition 
point of the two minerals. 

(1026) Fracture and flow in stressed solids. 
Roy W. Goranson. Trans. Amer. Geo- 
phys. Union, 21st annual meeting, pp. 
698-700 (1940). 

A stressed solid may deform permanently by 
rupture, which is an elastic breakdown, or by 
plastic flow, which involves a change-of-phase 
mechanism. Generally these two effects are com- 
bined. The relation of the latter mechanism to 
metamorphic processes and to deep-focus earth- 
quakes is discussed. The inadvisability of apply- 
ing the term viscosity to plastic-flow phenomena 
is also pointed out and substitution of a more 
general term suggested. 

(1027) Review and discussion of article by L. C. 
Graton, "Nature of the ore-forming 
fluid," Econ. Geol., vol. 35, pp. 197-358. 
Earl Ingerson and George W. Morey. 
Ibid., pp. 772-785 (1940). 

Graton's paper is discussed, parts of it in 
detail, under the following heads: 

1. State of solutions. It is agreed that ortho- 
magmatic solutions (i.e., the magma itself) are 
probably never above their critical temperature. 
However, magmatic emanations in equilibrium 
with the magma are almost certainly gaseous 
near the magma, but may condense to liquid 
where the temperature is low enough. The 
transport of nonvolatile material by gaseous 
solution is shown to occur in important amounts, 
and semiquantitative data are given. The im- 
possibility of evaluating the relative importance 
of liquid and gaseous solutions from field evi- 
dence is pointed out. 

2. Mechanism of separation. If ore-forming 
fluid is separated as a different phase from the 
magma, both field and laboratory evidence are 
more nearly in accord with reparation as a 
gaseous phase than with separation as an im- 
miscible liquid. 

3. Timing. The separation of a different phase 



52 



CARNEGIE INSTITUTION OF WASHINGTON 



is thought of as a continuous process. The 
separated phase can have important effects early 
in the cycle, but probably becomes more im- 
portant as an ore-forming fluid late in the cycle. 

4. Motive power. Gas pressure is considered 
to provide at least part of the propelling force. 
Collapse of the roof would tend to pump com- 
pressed gaseous as well as liquid solutions up- 
ward. 

5. Deposition: (a) State. Three cases are men- 
tioned, and the impossibility of telling from 
field evidence whether the solutions were liquid 
or gaseous is pointed out. (b) Alkalinity. The 
character of the solutions with respect to alka- 
linity or acidity is a problem that must be worked 
out for each individual deposit. 

(1028) Physical effects of extreme pressures. Roy 
W. Goranson. Scientific Monthly, vol. 51, 
pp. 524-535 (1940). 

The first part of the paper presents, with 
some illustrative examples, a generalized picture 
of the kinds of change expected at higher 
hydrostatic pressures. The relation of some 
recent developments in theoretical physics to 
certain ultra-high-pressure phenomena is also 
indicated. In the discussion of practical utiliza- 
tions it is shown why certain compromises must 
be made with theoretical expectations and why 
metastable systems are able to exist for long 
periods of time. The design of high-pressure 
assemblages is treated in the second part of the 
paper, not only for its own sake but also be- 
cause it illustrates the important field of non- 
uniform pressure phenomena. In fact, it was 
only through a recent theoretical development 
in this field that the feasibility of extending 
the previous experimental pressure range very 
materially was made evident. An example of 
the application of this hypothesis is given by a 
two-stage cascaded pressure device. 

(1029) Dehydration of pollucite. Michael 
Fleischer and C. J. Ksanda. Amer. 
Mineralogist, vol. 25, pp. 666-672 (1940). 

Samples of pollucite from two localities have 
been studied under the microscope and by 
means of X-rays before and after dehydration. 
This study is further evidence that the water 
present in the mineral is not an essential part 
of the crystal lattice. The shape of the dehydra- 
tion curve is not, in this case at least, a reliable 
means of deciding the role of water in a mineral. 

(1030) Annual Report for the year 1939-1940. 



(1031) Potentiometers for thermoelectric meas- 
urements. W. P. White. Symposium on 
"Temperature: its measurements and 
control in science and industry" (Amer. 
Inst. Physics), pp. 265-278. New York, 
Reinhold Pub. Corp. (1940). 
Leakage control by shielding. W. P. 
White. Ibid., pp. 279-283 (ic 



Potentiometers for Thermoelectric 
Measurements 

In 1905 the beginnings of a wide use of 
thermels led to a demand for potentiometers 
capable of measuring to 0.1 microvolt, or even 
somewhat better. The chief obstacle was in- 
trusive electromotive forces, the worst of which 
came from the switches. By 1908, means, seven 
in all, had been devised for overcoming this 
obstacle. The method was not to redesign the 
switches, but to arrange them so that their 
intrusives did not get into the galvanometer cir- 
cuit. This greatly eased the burden on the most 
important device of all, the eliminating switch, 
which removes the error from all thermal in- 
trusives. A parallel development was two devices 
for rapid reading, the provision for reading 
two figures on the galvanometer, and, in read- 
ing several thermels along together, a selector 
switch for the dials which worked together with 
the one for different thermels. 

Twenty or thirty years later, potentiometers 
are being improved so that the intrusives in 
them are nearly or quite as small as 0.00 1 
microvolt. This improvement is at present of 
no particular advantage except as it is used to 
enable Wenner's very rapid eliminating switch 
to be employed. This switch may often give 
several times the precision of the older methods, 
but its advantage is confined to the measure- 
ment of constant voltages, and observations 
with it are slower than by the older rapid 
methods. 

Leakage Control by Shielding 

An equipotential leakage shield, consisting of 
metal plates suitably connected together, inter- 
vening between a galvanometer system and its 
environment, will absorb leakage currents from 
outside, shunting them completely away from 
the system, and thus enabling comparatively 
inferior insulation to give better results than 
almost the best can do without the shield. Such 
a shield is best extended into electric furnaces 
into which thermels are inserted. Methods less 
effective, but often easier and therefore some- 
times preferable, are also discussed. 



GEOPHYSICAL LABORATORY 



53 



(1032) Temperatures of volcanoes, fumaroles, 
and hot springs. E. G. Zies. Symposium 
on "Temperature: its measurements and 
control in science and industry" (Amer. 
Inst. Physics), pp. 372-380. New York, 
Reinhold Pub. Corp. (1940). 

The obvious emission of heat associated with 
volcanic activity and with the related fumarole 
and hot-spring manifestations has provoked 
much speculation as to its origin. It has also 
been responsible for an enormous amount of 
laboratory investigation of the temperature range 
within which the mineral species that make up 
igneous rocks have been formed. The determi- 
nation of the temperatures that prevail during 
these periods of thermal activity has therefore 
received the attention of many investigators. 

In this paper the various temperature-measur- 
ing devices used in these investigations at specific 
areas are described and the results obtained are 
presented. The limitations of the methods and 
the difficulties encountered when they are ap- 
plied in the field are given in detail. 

The results show that temperatures as high 
as 645 ° C were found in the steam vents of the 
extensive fumarolic area of the Valley of Ten 
Thousand Smokes. They also show that the 



temperature of lavas ranges from the 725 ° 
characteristic of the sluggishly moving andesitic 
lava of Santiaguito, in Guatemala, to the 1150 
characteristic of the rapidly moving basaltic 
lava of Nyamlagira, in Africa. 

The determination of temperatures, together 
with the study of the chemical environment of 
these thermal areas, has suggested many addi- 
tional problems for investigation in the labora- 
tory, especially the role played by vapor-phase 
activity in transporting various constituents of 
the igneous materials toward the surface. 

(1033) Automatic control of laboratory furnaces 
by the Wheatstone bridge method. How- 
ard S. Roberts. Symposium on "Tem- 
perature: its measurements and control 
in science and industry" (Amer. Inst. 
Physics), pp. 604-610. New York, Rein- 
hold Pub. Corp. (1940). 

Regulators of this type are in constant use in 
the Geophysical Laboratory for control of high 
temperatures. The paper includes a general 
discussion of the Wheatstone bridge type of 
controller and its applicability. It brings up to 
date material presented in Laboratory publication 
no. 573 (see report for 1925-1926, pp. 69-70). 



BIBLIOGRAPHY 



Barth, T. F. W. Geysir in Iceland. Amer. Jour. 

Sci., vol. 238, pp. 381-407 (1940). 
Fleischer, M., and C. J. Ksanda. Dehydration 

of pollucite, Amer. Mineralogist, vol. 25, 

pp. 666-672 (1940). 

See Morey, G. W. 

Gibson, R. E., and O. H. Loeffler. Pressure — 
volume — temperature relations in solutions. 
Ill: Some thermodynamic properties of mix- 
tures of aniline and nitrobenzene. Jour. 
Amer. Chem. Soc, vol. 61, pp. 2877-2884 

(i939)- 

The effects of pressure, tempera- 
ture and chemical composition on the ab- 
sorption of light by mixtures of aromatic 
amines and nitro compounds. Jour. Amer. 
Chem. Soc, vol. 62, pp. 1324-1334 (1940). 

Goranson, R. W. Physics of stressed solids. 
Jour. Chem. Phys., vol. 8, pp. 323-334 
(1940). 

"Flow" in stressed solids: an interpre- 
tation. Bull. Geol. Soc. Amer., vol. 51, pp. 
1023-1033 (1940). 

Fracture and flow in stressed solids. 

Trans. Amer. Geophys. Union, 21st annual 
meeting, pp. 698-700 (1940). 

Physical effects of extreme pressures. 

Scientific Monthly, vol. 51, pp. 524-535 
(1940). 



Griggs, D. Experimental flow of rocks under 

conditions favoring recrystallization. Bull. 

Geol. Soc. Amer., vol. 51, pp. 1001-1022 

(1940). 
Henderson, E. P. See Ksanda, C. J. 
Ingerson, E. Fabric criteria for distinguishing 

pseudo ripple marks from ripple marks. 

Bull. Geol. Soc. Amer., vol. 51, pp. 557-570 

(1940). 

and G. W. Morey. Review and dis- 
cussion of article by L. C. Graton, "Nature 
of the ore-forming fluid," Econ. Geol., vol. 
35, pp. 197-358. Ibid., pp. 772-785 (1940). 

Kracek, F. C. Phase equilibrium relations in 
the system Na 2 SiO a — Li 2 SiO a — Si0 2 . Jour. 
Amer. Chem. Soc, vol. 61, pp. 2863-2877 

(i939)- 
Ksanda, C. J., and E. P. Henderson. Identifica- 
tion of diamond in the Canyon Diablo iron. 
Amer. Mineralogist, vol. 24, pp. 677-680 

(i939)- 

■ See Fleischer, M. 

Loeffler, O. H. See Gibson, R. E. 

Morey, G. W., and M. Fleischer. Equilibrium 
between vapor and liquid phases in the sys- 
tem C0 2 — H 2 0— K 2 0— Si0 2 . Bull. Geol. 
Soc. Amer., vol. 51, pp. 1035-1057 (1940). 

See Ingerson, E. 



54 



CARNEGIE INSTITUTION OF WASHINGTON 



Piggot, C. S., and W. D. Urry. The radium 
content of an ocean-bottom core. Jour. 
Wash. Acad. Sci., vol. 29, pp. 405-410 

(i939)- 

Posnjak, E. Deposition of calcium sulfate from 
sea water. Amer. Jour. Sci., vol. 238, pp. 
559-568 (1940). 

Roberts, H. S. Automatic control of laboratory 
furnaces by the Wheatstone bridge method. 
Symposium on "Temperature: its measure- 
ments and control in science and industry" 
(Amer. Inst. Physics), pp. 604—610. New 
York, Reinhold Pub. Corp. (1940). 

Shepherd, E. S. Note on the fluorine content 
of rocks and ocean-bottom samples. Amer. 
Jour. Sci., vol. 238, pp. 1 17-128 (1940). 

Notes on fluorine. Bull, volcanolo- 

gique. (In press; publication delayed because 
of international conditions.) 



Urry, W. D. See Piggot, C. S. 

White, W. P. Potentiometers for thermoelectric 
measurements. Symposium on "Tempera- 
ture: its measurements and control in science 
and industry" (Amer. Inst. Physics), pp. 
265-278. New York, Reinhold Pub. Corp. 
(1940). 

Leakage control by shielding. Sym- 
posium on "Temperature: its measurements 
and control in science and industry" (Amer. 
Inst. Physics), pp. 279-283. New York, 
Reinhold Pub. Corp. (1940). 

Zies, E. G. Temperatures of volcanoes, fuma- 
roles, and hot springs. Symposium on "Tem- 
perature: its measurements and control in 
science and industry" (Amer. Inst. Physics), 
pp. 372-380. New York, Reinhold Pub. 
Corp. (1940). 



DEPARTMENT OF TERRESTRIAL MAGNETISM 

Washington, District of Columbia 

JOHN A. FLEMING, Director 
O. H. GISH, Assistant Director 

SUMMARY 



The activities of the Department in earlier 
years had to be directed chiefly toward obtain- 
ing field- and observatory-data, but during 
this report-year (July i, 1939 to June 30, 
1940) continued reduction and intensive 
study of results previously obtained and de- 
velopment of attack by experiments in the 
laboratory have constituted the major portion 
of the Department's work. Improved delinea- 
tion of fact and extension of theory have 
emerged from these investigations. An im- 
portant factor in such delineation and exten- 
sion, particularly in terrestrial magnetism and 
electricity, is the interchange of ideas and the 
coordination of effort facilitated by interna- 
tional scientific gatherings. Three such con- 
gresses were held in the United States during 
the report-year. These were the Sixth Pacific 
Science Congress, in San Francisco; and the 
Seventh (triennial) Assembly of the Inter- 
national Union of Geodesy and Geophysics 
and its seven Associations, and the Eighth 
American Scientific Congress, in Washington. 
In all these, papers, discussions, and resolu- 
tions pertaining to geomagnetism and its 
associated fields were outstanding features. 
The staff of this Department participated 
actively in the first and last, and took a lead- 
ing part in preparing and conducting the 
second. 

Research in geomagnetism as a world-wide 
geophysical phenomenon requires close inter- 
national collaboration, since many geomag- 
netic and geoelectric phenomena cannot be 
successfully studied unless they are observed 
all over the globe. The importance of a geo- 
physical congress therefore lies partly in the 
exchange of ideas and in the personal contact 
of scientists whose institutions happen to be 
in different countries, but mainly in obtaining 
agreement on the kind of observations needed 



in each country to stimulate world-wide co- 
operative projects and to organize and stand- 
ardize the work and the dissemination of 
results. 

Geomagnetic investigations. The disrup- 
tion caused by the war threatened to stop the 
procuring of much indispensable information, 
for instance, the scheme of magnetic charac- 
terization indicating for every day the degree 
of disturbance. The international magnetic 
character-figure, ranging from 0.0 to 2.0, is 
an average of qualitative estimates rather 
vaguely defined, made at about fifty observa- 
tories all over the world; its standard of 
measurement changes when a number of 
reporting stations drop out. Mainly through 
the initiative of members of this Department, 
a new scheme for a quantitative measure of 
magnetic activity has been introduced by the 
International Association, namely, the mag- 
netic 3-hour-range index K between o and 9. 
Through joint studies with the U. S. Coast 
and Geodetic Survey, the X-index was estab- 
lished as a valuable abstract of the magneto- 
grams, providing even single observatories 
with good estimates of world-wide magnetic 
conditions. This index is now currently de- 
rived from data obtained by seven American- 
operated observatories, and is published 
weekly by Science Service. It gives, for the 
first time, a detailed homogeneous series for 
the intensity of solar corpuscular radiation 
affecting the Earth, useful both in its terres- 
trial aspect — as in scientific or commercial 
radio work — and for its bearing on solar 
physics. Violent magnetic storms with K = g 
occur only a few times near a sunspot- 
maximum, but it is equally rare that any full 
3-hour interval is perfectly free from disturb- 
ance. This means that the Earth is almost 
constantly, even near sunspot-minimum, 



55 



56 



CARNEGIE INSTITUTION OF WASHINGTON 



under the influence of (presumably solar) 
particles, weak as this influence may be at 
times. 

The intensity of the ionizing solar wave- 
radiation absorbed in the ionosphere on the 
daylight hemisphere can likewise be meas- 
ured geomagnetically in the amplitudes of 
the solar daily magnetic variation. The rec- 
ords of horizontal intensity at the Huancayo 
Magnetic Observatory, in which the magni- 
tude of the solar daily magnetic variation is 
exceptional, were analyzed for the whole 
available series, 1922-1939, and a measure for 
the ionizing solar wave-radiation was ab- 
stracted and compared with the relative sun- 
spot-numbers, as the only available complete 
series of daily measures of solar activity. The 
correlation-coefficient between them is +0.92 
for monthly means, +0.97 for quarterly 
means, and -f 0.984 for annual means. These 
are the closest established relations so far 
found between phenomena on the Sun and 
Earth. The geomagnetic measure for the 
ionizing solar wave-radiation is being im- 
proved by combining data from several ob- 
servatories in order to arrive at daily values. 

In connection with this work on data from 
Huancayo, the Moon's influence on the hori- 
zontal force was next isolated and studied. 
Certain additional features of that influ- 
ence were also found, all of which can be 
interpreted by the dynamo-theory as the mag- 
netic field of electric currents induced in the 
oscillating ionosphere by the Earth's perma- 
nent magnetic field. These currents must 
flow low in the ionosphere, where recombina- 
tion of ions is rapid, because the lunar varia- 
tion is found to be confined to the daytime; 
neither primary ionospheric currents nor 
secondary currents induced within the Earth's 
body cross the night hemisphere near the 
equator. The ionospheric air-motions appear 
to be much more dominated by tidal oscilla- 
tions than are the winds near the ground, 
because the Moon's geomagnetic effect is 
plainly expressed in the magnetograms even 
for single days. The partial tides connected 
with the Moon's varying distance from the 
Earth are clearly recognized in the geomag- 
netic records, but the relations of the ampli- 



tudes and phase-angles of the geomagnetic 
partial tides to the main semidiurnal tide 
differ significantly from those in the gravita- 
tional tidal forces. The study of geomagnetic 
tides provides thus a new approach to the 
study of resonance-phenomena in atmospheric 
oscillations. 

A better understanding of the Earth's 
general magnetic field and of its secular varia- 
tion was obtained through a representation of 
the field by a series of properly disposed ele- 
mentary magnets. From this new representa- 
tion, inferences may be drawn regarding the 
depth at which the magnetic field originates 
and the quantitative relation between the 
general field and its secular variation. The 
general magnetic field may be effectively re- 
solved into a symmetric field and a residual 
field. The inferences drawn from the repre- 
sentation are that the residual field originates 
at no greater depth than the surface of the 
Earth's inner core, which seismological evi- 
dence indicates is in a fluid state, and that 
secular change is a continual modification of 
this residual field — a modification so exten- 
sive that in the course of a few centuries its 
entire structure is completely changed. No 
inferences may be drawn regarding the depth 
at which the symmetric field originates or 
whether it also is affected by secular change. 
It is clear that secular change does not affect 
this symmetric field to so great an extent 
proportionally as it does the residual field. 

Studies of magnetic storms suggest that the 
atmospheric current-system responsible for 
the daily variation of disturbance arises in 
part from electromotive forces generated 
mainly along the auroral zone. 

A general theory of analysis of surface 
magnetic fields was developed. This method 
permits analysis of fields (such as those of 
magnetic storms) for which the method of 
spherical harmonic analysis is impracticable. 
It is based on Green's theorem and permits 
the separation of an observed surface mag- 
netic field into its parts of external and in- 
ternal origin. An application to the field of 
magnetic storms, hitherto not analyzed for 
high latitudes of the Earth, shows that about 
60 per cent of the observed field is of external 



DEPARTMENT OF TERRESTRIAL MAGNETISM 



57 



origin; departures from this value are greatest 
near the auroral zone. The method also af- 
fords a convenient means of estimating the 
errors introduced, in effecting approximate 
analysis, by assuming parts of the Earth's sur- 
face to be plane. An extension of the theory 
permitting estimates of the space-distribution 
of electric currents responsible for the field is 
being attempted with a view toward its utility 
in geomagnetism and geophysical prospecting. 

The magnetic storm of March 24, 1940, 
probably the greatest magnetic storm ever 
recorded, was an event of unusual geo- 
physical interest. Disturbances of radio com- 
munication during great magnetic storms be- 
cause of concomitant effects on the iono- 
sphere, and disruption of wire-communica- 
tion through electric currents induced in the 
Earth, have frequently been noted, but during 
this storm the induced earth-currents attained 
such magnitude that electric power-systems 
were severely affected — the first time such 
effects have ever been reported. Computa- 
tions were made of the intensity of currents 
which could be produced by magnetic 
changes, and for extreme cases it was found 
to be sufficient to produce the observed effects 
on power-lines. Thus, an increased practical 
importance of research in terrestrial magnet- 
ism has been shown, for the lengthy observa- 
tions extending over a century supply definite 
information on the probability of occurrence 
of such storms and therefore on the extent to 
which it is advisable to revise electrical instal- 
lations to avert their effects. To study these 
great magnetic storms more thoroughly and 
to supply complete and accurate records, a 
wide-range magnetic recorder has been in- 
stalled in the Standardizing Magnetic Ob- 
servatory of the Department at Washington, 
capable of recording greater variations than 
have ever been observed. 

The continued study of the magnetic decli- 
nation in past geological ages through meas- 
urements on a more extensive collection of 
varves from the Hartford series shows that 
the deduced declinations in the varves col- 
lected at East Windsor Hill are in approxi- 
mately the same direction as those at East 
Hartford. Further publications on this prob- 



lem will not be attempted, however, until a 
more adequate series has been collected. 

The attainment, in March 1940, of hydro- 
static pressures in excess of 200,000 atmos- 
pheres at the Geophysical Laboratory made 
possible further measurements on the shift of 
the Curie temperature. For a cadmium- 
magnesium-iron spinel and with pressures to 
10,000 atmospheres, a shift of the order of 
o?oo2 C per bar was found. The extension of 
these results to some of the deep-lying con- 
stituents of the Earth's crust promises to have 
an important bearing on a theory of the 
Earth's permanent magnetic field. 

The anomalies in magnetic vertical in- 
tensity measured last year in the vicinity of 
the volcano Santa Maria in Guatemala were 
compiled. Since these data were insufficient 
in number to afford a satisfactory geological 
interpretation, they were supplemented by 
nearly 750 additional observations early in 
1940; analysis of these data is under way. 

Terrestrial electricity. A critical discussion 
on ionic equilibrium — the ion-population 
problem — in the atmosphere indicates sources 
of possible error. The equations for ionic 
equilibrium show that the fraction of the 
nuclei of condensation in the atmosphere, 
which are electrically neutral, is related to the 
geometrical mean of two ratios corresponding 
to two pairs of parameters in the equations. 
The value of the fraction previously found at 
Washington is greater than any of those re- 
ported for other places and is about 50 per 
cent greater than the average. This was con- 
firmed by a more extensive series of observa- 
tions made by another observer using different 
equipment and exercising particular precau- 
tions to avoid sources of error. Another 
equally important and quite unexpected result 
is that this fraction (0.75) is the same for air 
in all conditions, in a closed room or outside, 
in the city or in the open country, and at 
night or in daytime. 

The analysis of the diurnal variation in the 
vertical electric conduction-current in the 
atmosphere at College, Alaska, indicated a 
local component which is not caused by here- 
tofore considered factors operating in the 
atmosphere adjacent to the Earth. That com- 



58 



CARNEGIE INSTITUTION OF WASHINGTON 



ponent, therefore, is thought to have broader 
geophysical interest than many local atmos- 
pheric-electric phenomena, some of which 
were subjects of investigation. 

From harmonic analyses of the data for the 
ii years from 1924 to 1934 at the Watheroo 
Magnetic Observatory for potential-gradient, 
positive and negative conductivities, air-earth 
current, ratio of positive to negative con- 
ductivity, and difference between positive and 
negative conductivity, the 24-hour wave was 
found to predominate in all cases. For poten- 
tial-gradient, agreement was good with the 
universal 24-hour wave found over the oceans 
from observations made aboard the Carnegie, 
except for the wet months May to August. 
The analyses show a lag of about 90 minutes 
for the 24-hour wave of the negative con- 
ductivity as compared with that of the posi- 
tive conductivity. The 24-hour wave in the 
air-earth current shows considerable seasonal 
range, the maximum occurring at about 19 11 
GMT in December and January, and at 23 11 
in July and August. The average magnitude 
of the air-earth current was about 10X10" 7 
esu, being about that found over the ocean 
aboard the Carnegie. 

Ionization as measured with a thin-walled 
chamber in a closed room is less when large 
ions are numerous than when they are few. 
Tests indicate that the diminution in ioniza- 
tion cannot be explained on the earlier pro- 
posed hypothesis that large ions falling out 
of the air carry radioactive material with 
them and consequently tend to clear the air 
of ionizing material. The phenomenon thus 
remains unexplained and invites additional 
experimental work. 

Experiments on large ions from gas flames 
indicate that the recombination-coefficient is 
not a constant, but diminishes from about 
15 X io"° initially to about 0.6 X io~ 9 in about 
90 minutes after the ions are formed. This 
diminution is explained as arising from a 
gradual increase in the average size, through 
recombination, of the large ions. 

Tests show that molecular ions are pro- 
duced in abundance by the action of ultra- 
violet light from a mercury-arc lamp. Numer- 
ous large ions are also found in air irradiated 



with the ultraviolet light. Preliminary tests 
have indicated that uncharged particles are 
produced by ultraviolet light and combine 
with the molecular ions and so produce large 
ions, the result being that the number of 
molecular ions present is greatly diminished. 
Assuming this mechanism, the rate of pro- 
duction of molecular ions was deduced and 
was found sufficient to account quantitatively 
for the increase in ionization required for the 
production of radio fade-out during a chro- 
mospheric eruption. 

Cooperation in the volcanological investi- 
gations of the Geophysical Laboratory con- 
sisted of two projects: (a) the design and 
construction of a portable "ionization-meter" 
which will provide information about the 
variation with position of the amount of 
radioactive matter in the air and of that in 
the Earth near the surface; (£>) surveys 
(December 1939 to February 1940) of the 
electrical resistivity of earth, particularly as a 
function of depth, at two sites in the highland 
volcanic region of Guatemala: one 11 km 
from the volcano Santa Maria, the other near 
Guatemala City. Preliminary analyses of the 
results obtained in these surveys show a very 
uniform structure and indicate that the beds 
of volcanic ash are of very great depth. 

Ionosphere. The accumulation of homo- 
geneous ionospheric data from the Watheroo 
and Huancayo magnetic observatories has 
made detailed analysis of associated iono- 
spheric and geomagnetic effects possible. The 
automatic equipment for observation of the 
ionosphere has been in operation for more 
than two years. Systematic changes in the 
ionosphere associated with geomagnetic ac- 
tivity have been found; these are not the same 
at different latitudes. Even small fluctuations 
in geomagnetism are accompanied by associ- 
ated changes in ion-density in the ionosphere 
at both observatories. Introduction of the new 
3-hour-range index, K, of geomagnetic ac- 
tivity facilitates the investigation of systematic 
changes. This investigation is the first step in 
separation of individual factors which are in- 
volved in the complicated changes in the outer 
atmosphere. 

The great magnetic storm of March 24, 



DEPARTMENT OF TERRESTRIAL MAGNETISM 



59 



1940 was associated with ionospheric changes 
of almost unique character. Coincidently 
with the beginning of the geomagnetic 
changes, the F 2 -layer was carried upward and 
disappeared. An unusual feature of this dis- 
turbance at Huancayo, where it occurred near 
midday, was the formation of a new F 2 -layer 
in place of the old. Because the original ion- 
density of the region was reduced to a low 
value, it may be regarded as an un-ionized 
atmospheric region which is suddenly exposed 
to uniform solar radiation. This offers an 
unusual opportunity to determine the rapidity 
with which new ionization is produced and 
existing ionization is destroyed. 

The important but troublesome problem 
of reducing measured virtual heights of iono- 
spheric regions to their actual heights was 
greatly simplified by development of graphic 
methods. The older methods were imprac- 
ticable of application to more than a very few 
records; the new method permits mass- 
reduction of observations to actual heights, 
so that the general knowledge of the iono- 
sphere has been greatly extended. 

Studies of the £-region of the atmosphere 
are being pursued vigorously, since it appears 
that within this region much of the solar 
influence is translated into geomagnetic effect. 
At present this investigation is assuming the 
following forms: (1) comparison of continu- 
ous observations of E-region ion-density at 
different locations with existing theories, and 
(2) investigation of special conditions during 
solar eclipses. Eclipse-observations were made 
during the solar eclipse of April 7, 1940; 
during the early stages of the eclipse, maxi- 
mum ion-density decreased more rapidly from 
normal-day conditions than was predicted, 
which would indicate that the Sun is not 
giving out the ultraviolet ionizing radiation 
uniformly from all parts of its surface. Plans 
have been perfected and arrangements made 
for similar observations at the Huancayo 
Magnetic Observatory during the solar eclipse 
of October 1, 1940. Experiments have been 
devised for precise measurements of height- 
variation of the E-layer. 

Rayleigh scattering from atmospheric gases 
in the path of an intense, modulated search- 



light-beam was measured to heights of 40 km; 
a 24-inch transmitting mirror and carbon arc 
were used as light-source, and a 30-inch 
mirror, with a photoelectric cell, and an 
amplifier were used in the receiver. Above a 
limit of haze, which varies from 4 to 10 km, 
the scattering agrees with that calculated for 
the usual atmosphere. This work showed that 
with a 60-inch mirror-system the height may 
be extended to 70 to 90 km. For this meas- 
urement, and also to determine the distri- 
bution of ozone below 20 km, a program us- 
ing 60-inch mirrors was begun in June 1940. 

Analysis of the world-wide cosmic-ray 
effects at the Cheltenham, Christchurch, God- 
havn, Huancayo, and Teoloyucan observa- 
tories was continued and excellent agreement 
was found between these effects at Huancayo 
and Teoloyucan and between those at Chel- 
tenham and Christchurch. There is a signifi- 
cant difference in the general trend in cosmic- 
ray intensity between that at Huancayo and 
Teoloyucan and that at Cheltenham and 
Christchurch, which may indicate an impor- 
tant change in the latitude-effect with time. 
(Further details regarding cosmic-ray re- 
searches are given in the report of the In- 
stitution's Committee on Coordination of 
Cosmic-Ray Investigations, pages 1 13-132.) 

Nuclear physics. The program of studies 
on the interactions of the primary particles of 
matter — protons, neutrons, and electrons — all 
of which have magnetic properties, was ad- 
vanced by several experiments. Measure- 
ments were made on the scattering of slow 
and fast neutrons by collisions with hydrogen 
nuclei (protons), on the resonance-scattering 
of protons by helium nuclei, and on the split- 
ting of the heavy-hydrogen nucleus into a pro- 
ton and a neutron by high-energy gamma 
radiation. An important part of the work on 
this type of fundamental analysis of the 
simplest things in Nature was the effort to 
improve technique, looking toward similar 
studies of interactions of particles at still 
higher voltages, corresponding to still more 
intimate collisions. The large electrostatic 
generator of the Atomic-Physics Observatory, 
built two years ago to extend these studies, 
then represented a necessary extrapolation of 



6o 



CARNEGIE INSTITUTION OF WASHINGTON 



technical knowledge, and much research and 
development have been needed to attain the 
expected limits of this equipment. This devel- 
opment is not complete, but definite progress 
has been made. 

Rapid progress was made in the plans to 
expand activities in nuclear physics to include 
cooperative projects which make use of arti- 
ficially radioactive tracers for studies of chemi- 
cal and biological processes (see Year Book 
No. 38). These plans center around a large 
cyclotron, which is to be a duplicate in all 
essentials of the 60-inch cyclotron at the 
University of California. The building, 
which includes laboratory-facilities for phys- 
ics, chemistry, and biology, was about 70 per 
cent complete in June, and the large parts of 
the cyclotron itself were designed and ordered. 
Assembly of the complete instrument is 
scheduled for the autumn and winter. Several 
investigations relating to photosynthesis, 
physiology of the embryo, genetics, and 
chemotherapeutic action, using tracers and 
nuclear radiations, were made during the 
year, in cooperation with other laboratories 
of the Institution, the National Cancer Insti- 
tute, and the Johns Hopkins University. 



Observatory-wor\. The observatories at 
Huancayo in Peru and at Watheroo in 
Western Australia continued their extensive 
programs of geophysical observations. Co- 
operative work was continued in atmospheric 
electricity at Apia, in atmospheric electricity 
and earth-currents at Tucson, and in mainte- 
nance of international magnetic standards at 
the Cheltenham Magnetic Observatory of the 
U. S. Coast and Geodetic Survey. 

Miscellaneous. The report-year saw the 
distribution, in August 1939, of Terrestrial 
magnetism and electricity (volume 8 of the 
series on "Physics of the Earth" sponsored by 
the National Research Council), eight of the 
fourteen contributors to which are members 
of the Department's staff; and the completion 
in June 1940 of the comprehensive two-vol- 
ume work Geomagnetism , by Research Asso- 
ciates S. Chapman and J. Bartels. These two 
treatises mark an epoch in the science of 
terrestrial magnetism and electricity. 

There were no retirements during the 
report-year. C. R. Duvall, who retired Janu- 
ary 31, 1937, after some twenty-four years of 
long and fruitful service as expert computer, 
died February 3, 1940. 



INVESTIGATIONAL AND EXPERIMENTAL WORK 



TERRESTRIAL MAGNETISM 



Those of the staff engaged in geomagnetic 
investigations were Berkner, Fleming, For- 
bush, Johnson, Johnston, Ledig, McNish, 
Torreson, and Vestine. Research Associates 
Bartels and Chapman took important part 
both through constructive advice and through 
investigations at Berlin and London; both 
were delegates at the Washington Assembly 
of the International Union of Geodesy and 
Geophysics, and the former was in residence 
at Washington from August 18, 1939 to 
September 23, 1940. 

Permanent Field 

Physical representation of the geomagnetic 
field. A new method of representing the 
geomagnetic field was developed (McNish). 



The geomagnetic field can be represented to 
a first approximation by a dipole of moment 
8.1 X io 25 CGS units appropriately placed 
near the center of the Earth, as has long been 
recognized. However, this single dipole 
represents only about 80 per cent of the ob- 
served field. It was found that the remainder 
of the field, the "residual field," can be repre- 
sented to within the accuracy of the observa- 
tions by 14 radially directed dipoles midway 
between the center and the surface of the 
Earth. This depth, which is identical with 
that at which seismological evidence indicates 
a discontinuity of the elastic properties of the 
Earth, was not arbitrarily chosen; placement 
of the hypothetical dipoles at a greater or 
lesser depth would have required a much 



DEPARTMENT OF TERRESTRIAL MAGNETISM 



61 



greater number for the same closeness of 
representation. This is regarded as evidence 
that the residual field has its origin between 
the inner core of the Earth and the surface. 
On the other hand, the quantity of magnetic 
matter necessary to produce the residual field 
is so great that it cannot be confined to the 
outer subsurface layers of the Earth's crust. 
This first establishment of some definite basis 
for estimating the depth at which the Earth's 
field originates is of fundamental importance 
in the development of any theory of the 
origin of that field. 

A similar representation of the field of 
magnetic secular variation was also developed, 
the dipoles being located at the same depth. 
However, a further restriction could be im- 
posed in this case, namely, that the dipoles 
be all of the same intensity. The two systems 
of dipoles, those for the residual field and 
those for the secular-variation field, tend to be 
"orthogonal," that is, the secular-variation 
dipoles are close to the zero isodynamic lines 
of the residual field. The average strength of 
the dipoles of the residual field is 1/80 of 
that of the centrally located dipole, while the 
dipoles of the secular-variation field are about 
1/100 as strong as those of the residual field. 
Accordingly, if secular variation were to pro- 
ceed at its present rate for 100 years or so, a 
new residual field would be built up differing 
markedly from that which exists at present. 
In this connection, all historic records of 
secular change suggest that it does not con- 
tinue in the same direction and sense at any 
one place for more than a century or so, and 
this generalization is supported by measure- 
ments of the residual magnetization of geo- 
logical sediments (see earlier annual reports). 

The concept strongly emphasized by this 
study is that the residual field, which accounts 
for about 20 per cent of the magnetic field 
observed at the surface, and its changes 
originate largely or entirely at a lesser depth 
than that of the Earth's fluid core. Secular 
change consists almost entirely of the changes 
in this residual field, the form of which is 
completely altered from century to century. 

In an investigation of the potential of the 
Earth's magnetic secular variation (Vestine) 



it was estimated that if secular change be 
attributed to changes in magnetization near 
the Earth's surface, there must be superposed 
upon the Earth's field yearly the field due to 
a thickness of 700 meters of radially magnet- 
ized material of unit magnetic moment in 
the region of active secular change just west 
of Africa. Such large changes in magnetiza- 
tion in the Earth's crust appear exceedingly 
improbable, as has been pointed out by others, 
so that attempted explanations of secular 
change on this basis are unsatisfactory. 

A paper on magnetic secular variation in 
the Pacific area (Vestine) presented at the 
Sixth Pacific Science Congress discussed, with 
special reference to the Pacific area, the iso- 
poric charts and equivalent magnetic shell 
for secular change (mentioned in the last 
annual report). The part of the secular- 
variation field observed near the boundary of 
the Pacific Basin may assist in interpreting 
changes in structural features of the Basin. 
The probable linear dimensions of these areas 
of localized secular change are probably 
smaller than for those of a more world-wide 
character, thus permitting their separation if 
sufficiently detailed surveys should become 
available. Magnetic profiles of the field taken 
across the boundary of the Basin would 
probably assist in marking out the limits 
of the boundary where this is uncertain (as 
in the South Pacific), and in conjunction with 
gravity-measurements should give useful in- 
formation respecting geological structure. 
The depth at which secular change originates 
is not likely to be greater than the horizontal 
width of the "vortices" appearing in the 
equivalent magnetic shell for secular change 
drawn for the Earth's surface. A part of 
secular change, likely to be larger where the 
crustal motions are larger, must of necessity 
originate in the Earth's crust. 

The technique of spherical harmonic analy- 
sis developed by Gauss in 1842 and later im- 
proved by Neumann, Schmidt, and Schuster 
has long furnished one of the most useful 
tools in the study of geomagnetism. Since the 
time of Gauss little attention has been devoted 
by geophysicists to the development of other 
techniques of field-analysis, although a num- 



62 



CARNEGIE INSTITUTION OF WASHINGTON 



ber of new developments in potential-theory 
have appeared during the past century in re- 
searches on hydrodynamics, heat, and sound, 
where boundary-problems analogous to those 
of geomagnetism sometimes appear. Since 
the Gaussian method of spherical harmonics 
proves inadequate in certain field-problems, 
an investigation has been undertaken of 
possible alternative methods offering greater 
scope in general application (Vestine). 

The Gaussian method is usually convenient 
and useful in the case of fairly simple geo- 
magnetic fields, but may become cumbersome 
and impracticable when the field-distribution 
over the Earth is complicated. In a field of 
this type a large number of spherical har- 
monic terms are usually required in obtaining 
a sufficiently close approximation to the field. 
In the case of magnetic storms a large num- 
ber of harmonics of high degree are required, 
and hence other techniques seem indicated. 
The same is true in general of other geo- 
magnetic fields, but in these the complicated 
features are relatively unimportant and can 
usually be neglected. In fact, since the compli- 
cated field-structures a>re frequently inade- 
quately measured, their inclusion may con- 
tribute to inaccuracies in analysis. The 
Gaussian method may even prove imprac- 
ticable in the case of very simple fields if 
these are of types expressible only by many 
important spherical harmonic terms. The 
fundamental limitation of the method is one 
of representation, a difficulty which can be 
overcome by the use of surface-integrals in 
field-analysis. 

The Gaussian method permits the separa- 
tion of an observed field over the Earth into 
its component parts of external and internal 
origin. A beginning has been made in the 
development of a more fundamental method. 
A general theorem, applicable to any regular 
closed surface S, gives the difference between 
the magnetic potentials of external and in- 
ternal origin in the form 
(V e -Vi) = (x/^ s [Z/r-Vb(i/r)/bn]dS 
where Z and V are the total vertical force and 
potential on S, respectively, n is the outward 
normal, and r is the distance from the point 
on the closed surface S at which (V e — Vi) 



is required, to the element of area dS. Since 
the potential V= (Vi-j- V e ) is known (or can 
be derived apart from a constant taken to be 
zero in geomagnetic applications using ob- 
served horizontal components of force), a 
separation of V into parts of external and 
internal origin is effected. This integral 
simplifies in the case of a sphere. An analo- 
gous expression is used in the separation for 
vertical force. Various surface-distributions 
of magnetic matter giving rise to the observed 
field have been obtained. The known solu- 
tions for the problems of Dirichlet and Neu- 
mann permit the continuation of the surface- 
values of the field into adjacent harmonic 
regions. The separation of the observed field 
into external and internal parts by means of 
surface-integrals is especially useful in the 
treatment of problems in which it is desirable 
to use data in the form of graphs, instead of 
in analytical form. A practical general method 
of computing possible external or internal 
current-distributions capable of reproducing 
the observed field has not yet been found, 
although solutions have been obtained using 
the alternating process of Schwartz. The 
possibility of using machine procedures in 
field-analysis is also being considered. 

Geomagnetism and volcanic structure. Re- 
duction of the results from the first magnetic 
survey of the volcano Santa Maria in Guate- 
mala was virtually completed. No alterations 
were made in the preliminary conclusions 
drawn from early reduction of a limited 
quantity of the data. In accordance with 
expectations, the magnetic field in the region 
of the volcano is extremely complex and 
requires many more data for interpretation 
than have been obtained. 

A detailed topographic map of the portion 
of the region covered by the magnetic survey 
was made, utilizing the auxiliary data ob- 
tained, and was supplied for the expedition 
of 1939-1940. On the basis of past experience, 
detailed plans were made for the magnetic 
program of this expedition, and instrumental 
equipment was prepared and calibrated. The 
magnetic profiles across the volcanic rift made 
at a number of places in 1940 by Green 
support in general the observations previously 



DEPARTMENT OF TERRESTRIAL MAGNETISM 



63 



made near Santa Maria; compilation of these 
data is not yet in form for detailed study and 
analysis. 

Effects of great pressure. The development 
at the Geophysical Laboratory of a cascade 
high-pressure bomb was successful and the 
new pressure-range of 200,000 bars was 
realized. This apparatus makes it possible 
for the first time to investigate the magnetic 
properties of the Earth's interior at pressures 
comparable to those which actually exist. At 
the same time, the technique of measuring 
Curie temperature was developed by Goran- 
son of the Geophysical Laboratory and by 
Johnson of the Department, and measure- 
ments were made on a cadmium-magnesium- 
iron spinel (supplied by Posnjak of the Geo- 
physical Laboratory) in the low-pressure re- 
gion up to 10,000 atmospheres. A shift of 
the order of 5 C for a change of pressure 
of 10,000 atmospheres was indicated. This 
large shift is supposed to be associated with 
the low Curie temperature of this spinel and 
is the first directly measured shift of this 
magnitude. The measurements required the 
development of an alternating-current bridge 
to measure changes in inductance of io" 10 
henry. It is believed that a modification of 
this method can be used at the superpressures 
just developed. This work, of course, is of 
great importance to theories involving the 
Earth's permanent magnetic field. 

Cosmic Relations 

Geomagnetic studies on fluctuations in 
solar radiation (Bartels). The theory of geo- 
magnetic time-variations and aurora, supple- 
mented by direct studies of the ionosphere 
by means of wireless waves, leads to the well 
known working hypotheses that the Sun, in 
addition to rays penetrating to the ground, 
sends us radiation to be classified as wave- 
radiation, W , and particles, P. W ionizes the 
day side of the ionosphere and is geomag- 
netically effective in the solar and lunar daily 
variations, S and L, while P reaches also the 
Earth's night side, mainly in polar regions, 
and produces auroral and magnetic disturb- 
ances with their associated effects. The in- 
tensities of both W and P vary in parallel 



with the 11-year sunspot-cycle (expressed in 
the relative sunspot-numbers R), but with 
the difference that P lags behind R, while 
W shows no lag. 

The fluctuations of both W and P are of 
fundamental interest for geophysics as well 
as for solar physics. Progress at the Depart- 
ment during the report-year is summarized 
below: 

As to solar corpuscular radiation P, various 
schemes for measuring it by its effect, the 
"magnetic activity," are in operation, espe- 
cially the "characterization" — international 
magnetic character-figure C for days, and 
American character-figure Ca for half-days — 
and the monthly w-measure expressing the 
variability of the equatorial "ring-current." 
Quantitative measures of activity for smaller 
time-units had always seemed desirable, but 
no adequate proposal had been made for a 
successful separation of the magnetic varia- 
tions due to P and to W until the practical 
and theoretical interest in ionospheric condi- 
tions led, mainly on the initiative of this 
Department, to action by the International 
Association of Terrestrial Magnetism and 
Electricity at its meeting in September 1939, 
at Washington, D. C. The Potsdam geo- 
magnetic index, introduced in 1938, was 
taken as a model for the new magnetic 3-hour- 
range index K. The new scheme was de- 
veloped by Bartels and H. F. Johnston in 
collaboration with Captain N. H. Heck, 
Chief of the Division of Terrestrial Magnet- 
ism and Seismology of the U. S. Coast and 
Geodetic Survey. 

Each collaborating observatory assigns to 
each 3-hour interval, beginning at oo h , 03 11 , 
. . . 21 11 GMT, one of the integers o to 9 as 
range-index K, by regarding the magnetic 
variations as superpositions of X-variations 
(effects of P to be measured) and of non- 
i^-variations (effects of W such as regular 
daily variations, or after-effects of P, to be 
eliminated). For each observatory, a perma- 
nent scale is adopted once for all, giving the 
limits within which the 3-hour ranges of the 
/^-variations, measured in units of force y 
(iy = 0.00001 CGS unit), define the index K. 
In practice the 3-hour range for each mag- 



6 4 



CARNEGIE INSTITUTION OF WASHINGTON 



netic element is defined as the difference 
between the highest and lowest deviation, 
within the 3-hour interval, from a smooth 
and regular daily variation to be expected 
for that element on a magnetically quiet day, 
according to the season, the sunspot-cycle, 
and, in some cases, the phase of the Moon. 
This range is considered for each of three 
rectangular field-components (X, Y, Z, or 
D, H, Z); only the largest of the three ranges 
determines K. 

The assimilation of frequency-curves guided 
the choice of scales for K. The ideal is to 
define them so that, in a sufficiently long 
time, for instance in the year 1938, each sta- 
tion assigns the same aggregate number of 
indices K = o, K=i, etc. 

The correlation between the indices as- 
signed for various observatories is high. Some 
stations exhibit a systematic daily variation 
of K; at Sitka (Alaska), for instance, the 
three intervals between local midnight and 
09 11 are more disturbed. Such regional fea- 
tures are faithfully indicated by K; for the 
purpose of measuring the intensity of the solar 
corpuscular radiation P, however, it is de- 
sirable to eliminate this daily variation. This 
is done by a second assimilation of frequency- 
curves which provides keys for transforming 
each index K into a reduced index K r . For 
each observatory twenty-four such keys are 
established, namely, for the usual three four- 
month seasonal groups, and for the eight 
intervals of the Greenwich day. In combining 
these reduced indices K r in a world-wide 
index K w as a measure of P, half weight is 
given to tropical observatories, where P can 
be less distinctly recognized than in polar 
regions. 

For longer intervals, such as days and 
months, other measures are derived from the 
indices K and K w , namely, the daily index B 
and the monthly average 3-hour amplitude A. 

Extensive tables of K, B, and A have been 
published, for the months January to June 
1938, and have been used for a thorough dis- 
cussion of the statistical and physical aspects 
of the new measures. At the end of the report- 
year tables for the years 1938 and 1939, based 
on data from seven American-operated ob- 



servatories and from Potsdam, Germany, 
were ready for publication. Weekly tables 
for K and K w are prepared on the basis of 
telegraphic reports from the five magnetic 
observatories of the U. S. Coast and Geodetic 
Survey and the Department's two observa- 
tories, Watheroo and Huancayo, and pub- 
lished by Science Service. Their usefulness 
is increasingly recognized, in particular for 
radio work, both scientific and commercial. 

Twenty-seven-day recurrences are better 
recognized in K than in the daily character- 
figures. In this connection, Bartels proposed 
a hypothetical division of magnetic storms 
into two types: In sweeping across the Earth's 
orbit, the front of a freshly formed stream of 
solar particles may either hit the Earth 
("nascent stream type") or not; in the latter 
case the rotating arm of the stream may 
eventually overtake the Earth from the eve- 
ning side ("mature stream type"). These 
possibilities must be considered when it is 
attempted to infer the travel-time of solar 
particles from the Sun to the Earth, from the 
time-interval between a solar flare and the 
subsequent outbreak of a magnetic storm. 

The fluctuations AW of solar ionizing 
wave-radiation W were studied in their effect 
on the solar daily variation S. This may be 
schematically described as due to two iono- 
spheric current-vortices with centers on the 
11 o'clock meridian, progressing along about 
35 latitudes, or, simpler still, as the magnetic 
field of a gigantic vertical horseshoe-magnet 
rotating around the Earth in the 11 o'clock 
meridian, with the south pole over 35 ° north 
latitude, and the north pole over 35 ° south 
latitude. These equivalent pictures illustrate 
those features in the daily variations of the 
north, east, and vertical-force components, 
X, Y , and Z, which express most clearly the 
intensity of S, and thereby AW, namely: near 
the equator, the daytime rise of X over the 
night-level; in northern middle latitudes, the 
daily wave in Y , with the morning maximum 
and the afternoon minimum, and the daytime 
decrease in Z; in southern middle latitudes, 
the daily variations in Y and Z as in the 
north, but with reversed signs. 

By induced currents in the Earth's interior, 



DEPARTMENT OF TERRESTRIAL MAGNETISM 



65 



S is magnified in X and Y and weakened 
in Z. This leaves, as most suitable for measur- 
ing AW, the daily ranges A (amplitudes) 
of X (or of the horizontal force H) near the 
equator, and of Y (or of the declination D) 
in middle latitudes. The annual variation 
of A is eliminated by computing for each 
calendar day a value of A corresponding to 
7^ = 50; the standardized deviations A A from 
this value, expressed as multiples of their 
standard deviations, measure AW. 

Studies according to this program were 
carried out for the horizontal intensity H at 
Huancayo (Peru), where S is of exceptional 
magnitude. The range A was defined as the 
excess of the 5-hour average og h to 14 11 
(standard time) over the night-level. This 
definition makes A satisfactorily independent 
of magnetic activity, that is, of corpuscular 
radiation P, up to the disturbance-level ex- 
pressed by the international character-figure 
C— 1.1; more disturbed days have so far been 
excluded from the computation. The lunar 
influence L appears in A as a wave with the 
period of half a month. In the average for 
the months November to February, near sun- 
spot-maximum ( JR = 93), this lunar semi- 
monthly wave has its maximum, ^ = 1497, 
4 days after new or full Moon, and its mini- 
mum, ^4 = 99Y, a quarter-month later. Elimi- 
nation of L is therefore necessary in order to 
arrive at the range As of S alone and at the 
measure for AW. A table of monthly means 
for AW, 1922-1939, was thus obtained and 
correlated with the relative sunspot-numbers 
R. The correlation-coefficients found are the 
highest ever obtained between phenomena on 
the Sun and on the Earth; they are +0.92 
for months, +0.97 for quarters, + 0.984 for 
annual means. These values prove, inci- 
dentally, that the sunspot-numbers R are a 
very good measure for wave-radiation W , 
although their standard may not be so well 
defined as that of the magnetic variations. 

Geomagnetic tides in the horizontal force 
at Huancayo. The lunar influence L on the 
daily ranges A of horizontal force H at 
Huancayo was studied in detail. In contrast 
with the solar daily variation S, L shows a 
large seasonal change, decreasing from Janu- 

8 



ary to June in the ratio 4 to 1. L changes 
with the sunspot-cycle nearly as much as S. 
Of the partial tides due to the changing dis- 
tance of the Moon from the Earth, N 2 can 
be clearly recognized, but its effect, as com- 
pared with that of the main lunar semidiurnal 
tide M 2 , is not an increase of amplitude at 
perigee but a shift in phase-angle. The geo- 
magnetic partial tides provide new observa- 
tional material with respect to the tidal air- 
motions in the ionosphere and to the 
resonance-effects in the atmospheric tidal 
oscillations. 

In the months December, January, and 
February, L is so large in relation to S that 
it can be recognized in the shape of the 
magnetogram for H on single days. Occa- 
sionally L luxuriates, so to say, and a model 
set of such "big L days" has been selected in 
which the lunar influence reaches 507 and 
more. Two conclusions can be drawn from 
the existence of such cases: The ionospheric 
air-motions must be dominated by tidal forces, 
much more so than the winds near the 
ground; and the strength of the L-currents 
in the ionosphere varies, on individual days, 
rather independently of the S-currents. 

A more detailed analysis of L, in hourly 
means of H, was restricted to the three 
months December, January, and February. 
A new formula was derived for expressing 
the lunar wave, which seems more adequate 
than the phase-law based on the harmonic 
analysis. L is confined to the daytime. This 
points theoretically to a lunar semimonthly 
wave in the ordinary daily means of H of 
approximately 6-y amplitude, which was 
actually traced in the observations. Further- 
more, the suppression of L at night as well 
as its symmetry with respect to noon proves 
that the L-currents flow rather low in the 
ionosphere. 

The computations on the lunar daily varia- 
tions in magnetic and meteorological data, 
done at London under Chapman's direction, 
were continued, though somewhat less in- 
tensively since the outbreak of war. A con- 
siderable volume of results of this work now 
awaits preparation for publication. 



66 



CARNEGIE INSTITUTION OF WASHINGTON 



Magnetic Disturbances 

The great magnetic storms of the present 
sunspot-maximum have all been accompanied 
by widespread disturbances of wire and radio 
communications; the unusually large one of 
March 24, 1940 even caused interference with 
electric power-systems. Study of the power- 
line effects reveals that they were caused by 
partial saturation of the transformer-cores due 
to large direct currents induced by the mag- 
netic changes. Transformers in which direct- 
current components of this type were in oppo- 
sition in individual coils were unaffected, but 
in certain regions, where other types of trans- 
former were in use, relays and other protec- 
tive mechanisms were operated by the storm. 
At a number of places where protective de- 
vices were unaffected, severe surges were 
recorded. Effects of this storm on power- 
systems extended throughout the northeastern 
United States and southeastern Canada, ap- 
pearing in all localities simultaneously to 
within a minute. The earth-potentials needed 
to produce these large direct-current com- 
ponents exceed any previously recorded. Cal- 
culations of the magnetic changes necessary 
to produce such earth-potentials were made. 
It was found that sudden magnetic changes 
in the region of the zone of great auroral 
activity need only be somewhat greater than 
the greatest changes yet observed in order to 
produce the effects. 

Study of great magnetic storms, as recorded 
at many magnetic observatories, suggests that 
with increasing amplitude of the perturba- 
tions there is also an increase in the rate at 
which a storm passes through its phases, both 
for the component dependent on universal 
time and for the component dependent on 
local time. 

A wide-range magnetic recorder was in- 
stalled in the Standardizing Magnetic Ob- 
servatory at the main laboratory of the De- 
partment at Washington, D. C, during April 
1940. Although regular magnetic observa- 
tions had been made at Washington in earlier 
years, this practice had been abandoned owing 
to artificial disturbances produced by electric 
cars. Such artificial disturbances, however, 
are of minor consequence for a wide-range 



magnetograph which is designed to supply 
complete records of the greatest magnetic 
storms. The increasing importance of record- 
ing such storms has been emphasized by the 
occurrences of the present sunspot-cycle, when 
extensive interference with electric com- 
munication- and power-systems has been 
experienced. 

The work on the disturbance-field of four 
moderate magnetic storms (Year Book No. 
38, p. 66) was extended and atmospheric 
current-systems were estimated for a number 
of additional hours of storm. During the 
initial phase of the storm of October 14, 1932, 
the intense polar circulations of current char- 
acterizing the main phase of storms were 
absent. As seen from above the geomagnetic 
north pole, the current-circulation was mainly 
directed eastward above the Earth, with an 
anticlockwise circulation centered south of 
the pole and on the daylit side of the Earth. 
Chapman noted that this vortex in the 
northern hemisphere was in good qualitative 
agreement with the theory of the initial phase 
of storms as developed by him and Ferraro; 
the vortex of current would be induced, in 
the face of an advancing solar stream of 
particles, by the geomagnet. Sufficient data 
for the southern hemisphere were not availa- 
ble to determine the possible presence there 
of a high-latitude vortex of current circu- 
lating in the opposite sense, as required by 
theory. An investigation is under way to 
check the agreement between theory and ob- 
servation, using more extensive data for sud- 
den commencements and the initial phase of 
storms. 

The current-systems for an hour of the 
initial and main phase of the storms were 
analyzed into their component D s t- and 
Sz>-parts. The current-systems for each phase 
estimated for the storm-time component D s t 
were the same in general type but opposite 
in sense, although much stronger westward 
currents flow along the auroral zone during 
the main phase. In the case of the disturbance 
daily variation Sd, the chief feature found 
during the initial phase was a great vortex of 
current over the daylit part of the northern 
hemisphere circulating anticlockwise as seen 



DEPARTMENT OF TERRESTRIAL MAGNETISM 



6 7 



from outside. This circulation was very dif- 
ferent from the corresponding So-circulation 
for an hour of the main phase, which showed 
characteristics agreeing closely in magnitude 
and sense with those of the current-system 
previously deduced by Chapman for the 
(averaged) main phase of 40 storms. It thus 
appeared that the current-systems deduced for 
individual hours of the main phase of moder- 
ate storms resemble fairly closely those found 
for the main phase averaged for many storms. 
During the main phase of storms the electric 
currents responsible are likely to flow near 
the E-region of the atmosphere, though there 
may be a part in the form of an equatorial 
ring-current at a distance of a few earth-radii, 
a conclusion arrived at through previous 
studies. The initial phase of storms has not 
yet been subjected to systematic study, and 
in the one case of the storm of October 14, 
1932, the suggestive agreement between 
theory and observation would, if real, place 
the probable origin of at least part of the 
currents beyond the atmosphere during the 
early hours of storm. 

The cooperation between Chapman and 
Dr. V. C. A. Ferraro on the theory of mag- 
netic storms was continued, and a further 
paper on the subject was completed; it gives 
further confirmation to the authors' theory 
of the first phase of a magnetic storm. 

The new analysis of the daily and irregular 
magnetic variations by Chapman and J. Crank 
had to be interrupted because of the war. 
Consideration of what had been done led 
Chapman to an examination of several 
general aspects of the geometry of isomagnetic 
charts, and the first of a short series of notes 
on the subject was prepared. It is expected 
that these notes will be of future service in 
the construction of all kinds of isomagnetic 
charts and diagrams of electric current- 
systems. 

An application of the Gaussian method to 
the mean hourly disturbance-field of a mag- 
netic storm was made (Vestine). Suitable 
coordinate nets were constructed permitting 
fairly speedy evaluation of the surface-inte- 
grals. It was found that about 60 per cent 
of the observed surface-field is of external 



origin, except in the region close to the 
auroral zone, where greater variability is 
shown. Estimates were also obtained of the 
error introduced in the use of plane-earth 
approximations in polar regions. 

Archives of Magnetic Records 

Additional miniature-film records of mag- 
netic records made during the Second Inter- 
national Polar Year were received for the 
archives maintained at the Department. The 
Polar- Year records are thus virtually complete 
and furnish a valuable assemblage of data 
which are immediately available for investi- 
gations in this country. Although the hazard- 
ous conditions existing abroad may result in 
destruction of many of the original records, 
the fruits of this cooperative international 
endeavor to obtain magnetic records from 
polar regions are certain of preservation 
through the existence of these archives in this 
country. 

Upper Atmosphere 

An experimental investigation of the upper 
atmosphere was made (Johnson, Hopkins, 
Mock) by measuring the light scattered from 
the beam of a modulated searchlight. Using 
refinements of technique, it was possible to 
detect an amount of light of 10 ~ 14 watt in the 
presence of a background light of io" 10 watt. 
With a carbon arc, a 24-inch transmitting 
mirror, and a 30-inch receiving mirror, the 
scattered light was detected from heights of 
40 km. The resolution was determined by 
the intersection of the searchlight-beam and 
the angle viewed by the photocell. The results 
show distribution of temperature and pres- 
sure in agreement with the observations of 
Hulburt, with an estimated temperature of 
— 55 C at 40 km; they indicated that with 
60-inch mirrors an ultimate height of 70 to 
90 km is possible and that the distribution of 
some of the atmospheric constituents, espe- 
cially ozone, can be determined. Work was 
begun in June 1940 (Aronson, Johnson) on 
an experimental program using 60-inch 
mirrors kindly loaned by the U. S. War 
Department. 



68 



CARNEGIE INSTITUTION OF WASHINGTON 



The work by Chapman and A. J. Majid 
Mian on Fourier and spherical harmonic 
expressions for the radiation-absorption and 
the ion-content at different levels in an ideal 
ionosphere was completed. (For this work 
the junior author was awarded the London 
degree of Doctor of Philosophy.) It is hoped 
later to prepare an account of this work for 
publication. 

Instrumental Developments 

Electromagnetic method. The work on the 
CIW primary magnetic standard (Johnson) 
consisted primarily in the accurate measure- 
ment of the mechanical dimensions of the 
coils to one part in a million and the con- 
struction of the complete instrument. Special 
measuring machines and measurement-stand- 
ards, necessary for the unique requirements 
for measurement, were made. These measure- 
ments include those for wire-diameter, coil- 
pitch, and coil-diameter. The wire-diameter 
was measured with a precise thermionically 
operated mechanical micrometer and a set of 
special gauges loaned by the National Bureau 
of Standards. No ellipticity of the wire and no 
significant change in diameter over the entire 
length of the winding were observed with an 
estimated probable error of less than 0.05 
micron. For the difficult measurements of 
pitch, the room-temperature was maintained 
to ±o?i C for determinations at 20 ° C and 
28 ° C to yield the temperature-coefficient. 
The results of several thousand measurements 
with line-standard and especially constructed 
cathetometer showed that variation in pitch 
was negligible and temperature-coefficient was 
about that of the pyrex coil-form; precision is 
estimated at ±0.25 micron. The measuring 
engine for determination of coil-diameter and 
a precise spherical-ended standard are com- 
pleted; the latter is spherical to better than 
0.1 micron, according to tests of the National 
Bureau of Standards. 

CIW induction-variometer. Operation of 



the CIW induction-variometer was continued 
by the staff of the Cheltenham Magnetic 
Observatory of the U. S. Coast and Geodetic 
Survey through the first half of April 1940, 
thus concluding over four years of experi- 
mental operation. It was then removed from 
Cheltenham and installed as the vertical- 
intensity instrument of the wide-range mag- 
netograph at the laboratory in Washington. 

Publications 

Publications relating to the geomagnetic 
researches are listed in the bibliography at 
the end of this report. Chapman and Bartels 
devoted much time to their text Geomag- 
netism, published by the Oxford University 
Press; despite delays caused by the war, the 
printing was completed in June 1940. 

Presidential addresses were made before 
two associations of the International Union 
of Geodesy and Geophysics in September 

1939, namely, "Tides in the air," by Chap- 
man, and "Trends of research in terrestrial 
magnetism and electricity," by Fleming. 

Bartels presented the following papers: 
"Geomagnetic tides at Huancayo," April 24, 

1940, before Section of Terrestrial Magnetism 
and Electricity of the American Geophysical 
Union; "The needle in the haystack, or sta- 
tistics in geophysics," March 21, 1940, before 
District of Columbia Branch of American 
Meteorological Society; and "Magnetic changes 
caused by the Sun and the Moon," May 4, 
1940, before the National Capital Amateur 
Astronomers' Association. McNish took part 
in an extemporaneous discussion of the great 
magnetic storm in progress in a nation-wide 
broadcast on March 24, 1940. He also ad- 
dressed the Edison Electric Institute at Chi- 
cago on "Magnetic storms" (May 7, 1940), 
the Philosophical Society of Washington on 
"The geomagnetic field and its variations" 
(March 2, 1940), the Washington Physics 
Colloquium on "Theories of the Earth's mag- 
netism" (April 10, 1940). 



DEPARTMENT OF TERRESTRIAL MAGNETISM 



6 9 



TERRESTRIAL ELECTRICITY 



In both branches of this subject, namely, 
atmospheric electricity and geoelectricity, a 
large share of the time of the members of the 
section is required for checking, controlling, 
and reducing data received from the observa- 
tories and for putting these in suitable form 
for final studies and publication. More infor- 
mation about this is given in the report on 
observatory-work. Special investigations, ex- 
periments, instrumental developments, etc., in 
progress at this Department during the report- 
year are outlined in the following paragraphs. 
The members of the staff participating in 
these are Gish, Rooney, Sherman, Torreson, 
and Wait. 

Atmospheric Electricity 

The broader objectives of investigations of 
this class of phenomena have been outlined 
in the introductions to the reports in Year 
Books Nos. 37 and 38. One of these objectives 
is to obtain a satisfactory understanding of 
the nature and origin of the "supply-current," 
that current which in an undetermined man- 
ner supplies negative electricity to the Earth 
at a rate of about 1800 amperes and thus 
maintains a negative charge on the surface in 
all areas where fair weather prevails. A meas- 
ure of this current is obtained only indirectly 
from measures of the current which flows 
from air to Earth in such areas. This, how- 
ever, depends to some extent upon meteoro- 
logical and other more or less local factors 
which have to be taken into account in 
attempts to arrive at a measure of the supply- 
current. In order to take account of these 
factors various auxiliary studies are made 
which often have interest in themselves and 
occasionally have specific bearing on other 
aspects of geophysics and practical affairs. 
Studies of this kind are accordingly promi- 
nent in this report. 

Diurnal and annual variation of the atmos- 
pheric-electric conduction-current at College, 
Alaska. Although it was reported last year 
that the average conduction-current at Col- 
lege, Alaska is practically the same as that 
indicated by measurements made at sea dur- 



ing cruises of the Carnegie and that, on the 
average for the year, the diurnal variation of 
this element closely resembles that found at 
sea, a continuation of that study has shown 
that when the data for the winter and sum- 
mer seasons are separately considered, the 
ratio between the current at College and that 
at sea undergoes a significant diurnal varia- 
tion. The character of the latter in summer 
is very different from that in winter, tending 
to have a double period in the former season 
and a single period with about half the range 
in the latter season. Several interpretations 
of this which are likely first to come to mind 
have been shown to be inadmissible, and 
some alternative interpretations, which re- 
quire verification in the future, have been 
considered in a paper by Gish and Sherman 
(Terrestrial Magnetism, vol. 45, pp. 173—190, 
1940). 

Just as the diurnal variation of the atmos- 
pheric-electric conduction-current gives an 
indication of a diurnal variation in the supply- 
current, when effects tending to distort the 
former are duly considered, so also one may 
examine the annual variation of the con- 
duction-current for an indication of the 
annual variation of the supply-current. The 
general character of the diurnal variation of 
the supply-current is now generally thought 
to be well established, and quantitative repre- 
sentations of this are viewed with confidence, 
but the situation with respect to the annual 
variation is unsatisfactory. Although it was 
reported some years ago (Wait) that the 
character of the diurnal variation of the 
potential-gradient, as indicated by data ob- 
tained at sea up to the end of cruise VI of 
the Carnegie, apparently undergoes an annual 
variation, and although this conclusion 
seemed to be supported by data obtained on 
cruise VII, the quantity and distribution of 
data and other circumstances were such that 
there was some ground for doubting the 
significance of this indication. A re-examina- 
tion of this question by approved statistical 
methods, started during the year (Sherman), 
seemed justified because it is thought that the 



70 



CARNEGIE INSTITUTION OF WASHINGTON 



annual variation in gradient at sea and that 
in the conduction-current there are practically 
alike; observations of the air-conductivity 
there showed no significant annual variation 
and little other systematic variation. The 
results of that analysis were also desired for 
comparison with those obtained from a corre- 
sponding analysis of the conduction-current 
at College. Although the analysis is not com- 
plete, there is already good indication that 
the change in character of the diurnal varia- 
tion during the year is significant at sea and 
at College and that this change is significantly 
similar at the two places. If the same corre- 
spondence is eventually found for a number 
of other places, well distributed in latitude, 
one may then begin to regard the annual 
variation of conduction-current at these places 
as chiefly an expression of the annual varia- 
tion in the supply-current. 

Analysis of atmospheric-electric data at 
W atheroo for 1924- 1934. Analysis of the 11 
years of data on potential-gradient and posi- 
tive and negative conductivity at Watheroo 
was begun by Wait and Torreson. Sum- 
maries, month by month, for "all complete 
days" and "selected days" for each of the 
three elements for the 11 -year period were 
prepared, giving diurnal-variation curves for 
each month, representing the mean curve for 
the period of observation. These summaries 
were then used to compute diurnal-variation 
data for air-earth currents for each month. 
Finally, harmonic analyses were made of the 
data for each month for "selected days" for 
potential-gradient, positive and negative con- 
ductivities, air-earth current, and ratio and 
difference of positive and negative conduc- 
tivities. For the 24-hour component it is of 
interest to note the following points: 

a) In potential-gradient, the maxima in the 
8 months from September to April fall be- 
tween 2i h and 23 11 120 east meridian time 
(13 11 to 15 11 GMT), which is in good agree- 
ment with the universal-time variations found 
over the ocean, but the 4 months from May 
to August have their maxima between 15 11 
and ij h 120 east meridian time, which is 
not in accord with the results over the oceans. 

b) The positive conductivity has its maxi- 
mum in each of the 12 months very close to 



o6 h 120 east meridian time, and the maxi- 
mum in negative conductivity falls about 1.5 
hours later, at 7^5. 

c) The ratio of positive to negative con- 
ductivity has its maximum in all months at 
approximately 24 11 120 east meridian time, 
and the difference between the two con- 
ductivities has its maximum at about oi h . 

d) The computed air-earth current has 
maxima for the 7 months from October to 
March lying between i 1 )^ and 4)^ 120 east 
meridian time; September has its maximum 
at 5^5, and the 4 months from May to August 
have their maxima between 6^5 and 7^5. 

The 12-hour component of the diurnal va- 
riation has also been obtained from the har- 
monic analysis of the several elements, and 
in each case it contributes but a small part 
to the observed diurnal variation. 

The monthly mean value of potential- 
gradient for the 11-year period 1924-1934 at 
Watheroo changes considerably through the 
year. For the 8 months from September to 
April it is between 85 and 95 volts per meter, 
whereas for May and June it is 70 volts per 
meter and for July and August 80 volts. 
Study of the rainfall-data for Watheroo re- 
veals that the months May to August are the 
rainiest of the year (two-thirds of the annual 
rainfall occurs in these months), and it is in 
these months that the monthly mean values 
of potential-gradient are lowest and the 24- 
hour component of the diurnal variation in 
this element is not in phase with the recog- 
nized universal 24-hour component which 
prevails over the ocean. In these months 
meteorological conditions doubtless play an 
important part in determining both the mag- 
nitude of the potential-gradient and the char- 
acter of its diurnal variation. 

A second interesting point is the difference 
in phase between the 24-hour component of 
the diurnal variation of positive and that 
of negative conductivity. The fact that the 
negative conductivity reaches its maximum 
1.5 hours later than the positive deserves care- 
ful study, because an understanding of the 
cause of this will help to clarify knowl- 
edge of ionic equilibrium in the atmosphere. 

The magnitude of the air-earth current, 
which is of considerable interest, is derived 



DEPARTMENT OF TERRESTRIAL MAGNETISM 



71 



from the monthly summaries of the computed 
current. The range in monthly mean value 
is from 8.0 to 11.2X10" 7 esu, with low and 
high values in February and July, respectively. 
In general, the wet months from April 
to September have the higher air-earth cur- 
rents, and the dry months have the lower 
currents. 

From the summaries of potential-gradient, 
comparison of "all complete days" with 
"selected days" shows in the months from 
December to March a prominent smoke-effect 
in the "all complete days" during the night 
hours. How completely the smoke-effect is 
avoided in the "selected days" is not known, 
but it is apparent that much of it has 
been. One of the papers presented during 
the year discussed this smoke-effect and other 
meteorological effects on the electrical condi- 
tion of the lower atmosphere. 

Effects of meteorological factors upon the 
atmospheric-electric elements at Watheroo 
and Huancayo. Further discussion (using 
added material) of the pronounced smoke- 
effect at Watheroo, where the smoke remains 
at low levels, and of the effect at Huancayo 
of large concentrations of condensation-nuclei, 
which must be present to considerable heights, 
concerned the high correlation found at 
Watheroo between fluctuations in wind- 
velocity and fluctuations in potential-gradient 
and conductivity. The fluctuations in poten- 
tial-gradient, conspicuous feature of the 
atmospheric-electric records, have periods of 
only a few minutes and have amplitudes of 
about 25 per cent of the value of the pre- 
vailing potential-gradient when the wind- 
velocity is 5 miles per hour, and 50 per cent 
when it is 10 miles per hour. The fluctuations 
in conductivity are much smaller but vary in 
a similar manner with changes in wind- 
velocity. The function of the wind in pro- 
ducing fluctuations in the atmospheric-electric 
elements is obscure, and it is possible that 
the wind is merely correlated with some 
more significant factor which is not yet re- 
vealed. 

Ionic equilibrium in the atmosphere. The 
electrical conductivity of the air depends 
chiefly upon the concentration of small ions 
of molecular dimensions. Changes in con- 



ductivity result in changes in potential- 
gradient and other electrical aspects, and on 
this account an understanding of the factors 
which determine the concentration of small 
ions is important to an understanding of 
the resultant phenomena. For a state of 
equilibrium, the concentration of small ions 
is expressed by a relation which is obtained 
by taking the rate of ion-formation equal to 
the sum of the rates of ion-destruction and 
ion-migration. The advantage to investiga- 
tion of having such a relation is obvious, and 
considerable advantage has already been 
realized, but an adequate approach to that 
goal has not yet been made. In a critical 
review completed during the report-year and 
reported at the Washington meeting of the 
International Union of Geodesy and Geo- 
physics, Gish and Sherman compared the 
values reported for the parameters which 
occur in such relations. The striking diversity 
of these values, though not definitely assign- 
able to particular factors, may in part be 
attributed to a difference from place to place 
in the character of the nuclei of condensation 
and of the large ions formed from these at the 
expense of small ions, but there appears to be 
evidence that a considerable part of the 
diversity is associated with the method of 
measurement and with that used in evaluat- 
ing the parameters. Furthermore, it is proba- 
ble that a state of perfect ionic equilibrium 
never exists in the atmosphere, but that the 
balance tips first one way and then the other. 
Because of this, the concept of equilibrium 
applies to the average rather than to the 
specific state, and accordingly the measure- 
ments which are used in evaluating the param- 
eters of the equations of ionic equilibrium 
must constitute an adequate sample and must 
be combined with due regard to the principles 
of statistics. The latter point is emphasized 
by the observation that in one of the few 
cases for which a full report of the primary 
data is available, it is found that the values 
of a parameter determined by two different 
methods of combining the primary data differ 
by 25 per cent. 

Although the situation with respect to the 
parameters is not satisfactory, it is evident 
from this study that the relations for ionic 



72 



CARNEGIE INSTITUTION OF WASHINGTON 



equilibrium, even in the simple form usually 
employed, express the average relation be- 
tween the several elements with a fair degree 
of approximation at the majority of places, 
but that the set of parameters required differs 
considerably from those which have generally 
been used. 

An investigation of the ratio of the concen- 
tration of the uncharged to that of the total 
nuclei (N /N a ) made during the past year 
(Sherman) provides additional ground for 
confidence in the validity of the equilibrium- 
relations for a rather wide range of conditions 
in the vicinity of Washington, namely, for 
air in a closed room in the laboratory, for air 
in the city, both in daytime and at night, and 
for air in the open country. No significant 
change in that ratio was revealed by a careful 
statistical analysis. That analysis is recom- 
mended for consideration by others who 
undertake such work in the future. Some 
investigators have reached conclusions which 
directly or indirectly imply that this ratio 
depends upon the concentration of nuclei 
and upon their size and nature, and that 
there is a considerable variation from night 
to day. The results outlined above indicate 
that those conclusions are not as generally 
applicable as may have been thought hereto- 
fore. Interest in undertaking this investiga- 
tion was in part stimulated by the fact that 
the value of (N /N a ), namely, 0.73, found 
from a series of measurements made at Wash- 
ington several years ago (Wait and Torreson) 
was greater than that found at any other 
place by other observers and was nearly 1.5 
times the value that was generally regarded 
as most representative. An equally large 
value (0.75) was found in this more extensive 
recent investigation. This signifies that the 
rate at which small ions in a given concen- 
tration combine with charged nuclei (large 
ions) is about six times that for combination 
with uncharged nuclei in the hypothetical 
case that the charged and uncharged nuclei 
occur in the same concentration. This also 
implies the same type of modification of the 
parameters which it was earlier found (Gish, 
annual report for 1937-1938) would bring 
the equilibrium-relations and the observations 



into agreement in several cases which had 
been cited by one investigator in support of 
his claim that the equilibrium-relations are 
not valid in the present form. Obviously the 
present investigation provides further evi- 
dence against that claim. 

The form of the equilibrium-relations 
usually employed is admittedly a first ap- 
proximation in which certain factors are 
neglected. A consideration of these neglected 
factors is definitely required in certain circum- 
stances. Thus it was found (Gish and Sher- 
man) that when a term which depends upon 
the drift of small ions in the electric field is 
included, the relations for ionic equilibrium 
give a satisfactory quantitative account of the 
ratio of positive to negative conductivity and 
the dependence of that ratio upon the poten- 
tial-gradient at College, Alaska, in winter 
when the air is very quiet. When the air is 
not quiet, turbulent stirring may effect a 
systematic migration of ions, both large and 
small, and of nuclei. Terms expressing the 
role of this factor may also be included in the 
differential equations of ionic equilibrium. 
Solutions of these more complete equations 
have been found only for special cases. One 
such solution, in which the total conductivity 
was assumed to be constant with elevation 
from the Earth's surface, was reported by 
Gish at the annual meeting of the American 
Geophysical Union in 1940. This solution 
shows that the observations made by Hogg 
of the vertical distribution of positive and 
negative conductivity in the first meter from 
the Earth's surface at the Kew Observatory 
may be quantitatively accounted for by the 
more general form of the equations of ionic 
equilibrium, provided the nuclei at the place 
of observation come chiefly from a distant 
source. 

The rate of ionization in the atmosphere 
plays an important role in determining the 
state of ionic equilibrium. Measurements of 
this element appear to be the least satisfactory 
of those which have to be used in evaluating 
the parameters in the equations of equilib- 
rium, and some of the diversity in the values 
published for those parameters may be 
attributed to this fact. In an endeavor to ob- 



DEPARTMENT OF TERRESTRIAL MAGNETISM 



73 



tain a better estimate of this element at Wash- 
ington, measurements have been made for 
several years using a so-called "thin-walled 
ionization-chamber" designed for continuous 
registration. 

In last year's report some interesting results 
obtained with the thin-walled ionization- 
chamber for different concentrations of large 
ions in a closed room indicated that the 
measured ionization diminished when the 
concentration of large ions in the air of the 
room increased. Among various explanations 
for this phenomenon, it was suggested that 
large ions fall to the floor, carrying radio- 
active matter collected on them out of reach 
of the apparatus. To test this possibility, a 
wide rim was attached around the base of the 
ionization-chamber to catch any large ions 
that might fall out of the air above it. Radio- 
active material caught on the rim would, 
however, still be near enough to the chamber- 
wall to produce ions inside the chamber, and 
would diminish or even reverse the effects 
originally found. Furthermore, with time, the 
accumulation of material on the rim might 
be expected to produce an increase in the 
ionization in the apparatus. Analysis of the 
records obtained with the rim in place showed 
none of these effects, and hence there is no 
support for the suggestion that radioactive 
material falls to the floor attached to large 
ions. The cause for the phenomenon thus 
remains unknown and calls for further ex- 
perimentation. 

The rate of combination of large ions is 
usually thought to be negligibly small in 
relation to other terms in the equations for 
ionic equilibrium, but that opinion is based 
chiefly on a single set of experiments made 
many years ago on ions from gas flames. A 
joint paper on this subject by Wait and 
Torreson was presented by Wait before the 
meetings of the American Physical Society in 
April 1940. The importance of a knowledge 
of the value of the recombination-coefficient 
between large ions of opposite sign, which 
enters into equations of ionic equilibrium in 
the atmosphere, has been discussed by Gish 
{Terrestrial magnetism and electricity, p. 183, 
1939). He expressed the hope that the wide 



difference between the value deduced by 
Hogg and that obtained experimentally by 
Kennedy from measurements on ions from a 
gas flame would stimulate investigators to re- 
peat Kennedy's measurements. During the 
past year, Wait and Torreson repeated those 
experiments, obtaining important and signifi- 
cant results which must, it appears, be taken 
into account when considering equilibrium- 
conditions for ions. Kennedy's value for the 
coefficient was 0.63 X io" 9 , whereas Hogg con- 
sidered the value to be about 17 X io -9 . Wait 
and Torreson found that the value of the 
coefficient did not remain constant, but 
rapidly diminished from the time the ions 
were first formed. The initial value was 
approximately that given by Hogg, but in 
90 minutes it had diminished to about the 
value given by Kennedy. In view of the fact 
that the coefficient decreases with increase in 
size of the ions, the reason for the diminu- 
tion in the value of the coefficient for large 
ions seems clear. There is, no doubt, an in- 
crease with time in the average size of the 
large ions in a given volume of air, for each 
time a pair of such ions combines, the re- 
sultant ion is probably larger. Sufficiently 
large concentrations of large ions were used in 
the experiments (initial value about 300,000 
per cubic centimeter) to ensure that recombi- 
nation of large ions of opposite sign would be 
the only important factor in causing the 
diminution in ion-concentration in the vol- 
ume under observation during the period of 
experiment {Physical Review, vol. 57, p. 1071, 
1940). 

The concentration of condensation-nuclei 
over the North Atlantic Ocean, measured by 
Davies on a round-trip cruise from North 
America to England in August and Septem- 
ber 1936, was analyzed and reported by Wait 
during the report-year. The mean of 186 sets 
of measurements is 751 nuclei per cubic 
centimeter. The value is usually relatively 
high to the leeward of land, even for distances 
as great as 200 miles from shore. The mean 
for 123 sets observed in the eastern two-thirds 
of the region covered, namely, 960 nuclei per 
cubic centimeter, was just one-half that for 
63 sets observed in the western third. This 



74 



CARNEGIE INSTITUTION OF WASHINGTON 



distribution is probably effected by the supply 
of nuclei from the North American continent, 
due to the prevailing westerly winds in this 
latitude. 

Some much needed supplementary atmos- 
pheric-electric observations could now be ob- 
tained with equipment of tested design. The 
urgent need of such observations has been 
further emphasized during the past year, the 
point being that in the interpretation of many 
features of the data which are now being 
obtained at observatories, the area of specula- 
tion remains too large. A paper in which 
this matter was stressed was presented at the 
Washington meeting of the International 
Union of Geodesy and Geophysics (Wait and 
Torreson). The plan for improving this 
situation is that for a period of one year at 
each observatory, successively, the present 
registrations (potential-gradient, positive and 
negative conductivity) be supplemented by 
simultaneous registrations of the rate of small- 
ion formation, and of the concentration of 
large, intermediate, and small ions, with 
equipment designed to be readily moved and 
quickly adjusted for operation. The informa- 
tion to be obtained from this supplementary 
program would serve the following purposes: 

(a) to make quantitative tests of interpreta- 
tions which at present can be only tentative; 

(b) to provide better quantitative information 
about the parameters which occur in the 
equations for ionic equilibrium in the atmos- 
phere and thereby facilitate the interpretation 
of atmospheric-electric phenomena generally; 
and (c) to make more satisfactory discrimina- 
tion between the electrical phenomena of local 
and of universal origin, in order that data 
pertaining to the latter may be used to deter- 
mine more definitely the characteristics of 
that fundamental element of atmospheric 
electricity, the supply-current. The scientific 
returns to be expected from the present 
limited program are practically all realized, 
but one may look with confidence for impor- 
tant additional returns from a short period 
of operation of the proposed amplified 
program. 

A "creep" in the setting of some elec- 
trometers of the portable torsion-type at rela- 



tively low sensitivity was examined by Gish 
and Sherman in the hope of finding the cause 
of this effect. In one instrument, which was 
being considered for use in biological investi- 
gations, and which showed an exceptionally 
large creep, it was found that the greater part 
of that effect was eliminated when a capsule 
of radium salt was placed near the elec- 
trometer. This together with other tests 
showed that the electrical conductance of the 
needle, probably near the ends, was inade- 
quate. It appeared, however, that a minor but 
detectable component of the effect was caused 
by some other factor. The latter was not 
investigated experimentally, but calculations 
indicate that it may be attributed to a defect 
in the method of supporting the torsion-fiber. 
Those calculations were qualitatively con- 
sistent with results of tests made on eight 
electrometers by Israel {Zeitschrift fur Instru- 
menten\unde, vol. 51, pp. 464-472, 1931). 
Although the ideal torsion-type, postulated by 
theory, would be electrically stable at a higher 
voltage-sensitivity than the single-fiber type, 
that ideal is apparently far from being realized 
in portable torsion-type electrometers available 
in this country. This examination indicated 
that some improvement in the technique of 
applying the conducting layer on the needle 
and in that of mounting the torsion-fiber is 
required in order to make this type compara- 
ble with, or superior to, the single-fiber type 
which has been in use for years in this 
laboratory. 

Error in measurements of the concentration 
of condensation-nuclei was found by Sherman 
to arise in an unexpected way. Such measure- 
ments are usually made with a so-called Ait- 
ken counter, which is essentially a small hand- 
operated expansion-chamber with a small 
expansion-ratio. In this it is essential that 
there be no leakage of air from outside into 
the chamber during an expansion, for such 
leakage may introduce nuclei in addition to 
those brought in with the measured sample 
of outside air, thereby erroneously increasing 
the "count." A leak of this character is re- 
vealed by droplets continuing to fall on the 
counting stage after repeated expansions. 
However, a contrary indication can no longer 



DEPARTMENT OF TERRESTRIAL MAGNETISM 



75 



be regarded as a sure criterion of freedom 
from sufficient leak to falsify the count in 
serious degree. This was shown by the fol- 
lowing observation. Measurements made 
nearly simultaneously with two counters, both 
apparently in good order, differed systemati- 
cally, the mean for one being about one-half 
that for the other. Tests with a manometer 
showed a leak in the one which gave the 
smaller count. After this defect was reme- 
died, the results from the two counters agreed. 
Now that errors of such origin are recognized 
and understood, it is seen that they may be 
avoided by setting the cock in such a way 
that the pressure in the chamber is brought 
to that of the atmosphere each time before the 
sample of air is admitted. 

Electrical phenomena associated with the 
evaporation and condensation of water. Dr. 
Ross Gunn, Research Associate, continued 
his experimental study of the electrical phe- 
nomena associated with the evaporation and 
condensation of water. He developed a new 
apparatus suitable for the study of contact- 
potentials, or contact-potentials with super- 
posed free charges, which extends a method 
previously outlined by him in the Physical 
Review (vol. 40, p. 307, 1932). Using the 
new apparatus, it has been observed that a 
discontinuity in contact-potentials of 0.26 volt 
occurs when a frozen raindrop melts and a 
water-surface is formed thereon. The outer 
surface becomes more positive on melting or 
more negative on freezing. This phenomenon 
may play a considerable part in the phe- 
nomena of electricity of thunderstorms. The 
measurements are tentative and will be 
checked with more satisfactory apparatus now 
under construction. 

Cooperation in atmospheric-electric wor\ 
of other investigators. A portable apparatus 
for use in determining the ratio of the con- 
centration of the uncharged to that of all 
nuclei of condensation in the atmosphere was 
designed by Gish and constructed in the 
Department's instrument-shop for use on the 
National Geographic Society— University of 
Virginia South Seas Expedition. When that 
expedition was indefinitely postponed because 
of developments in Europe, this apparatus 



was used by Sherman for the series of meas- 
urements mentioned earlier in this report. 

As part of the cooperation with the Geo- 
physical Laboratory in volcanological investi- 
gations, a portable "ionization-meter," de- 
signed by Gish following the general features 
of the "ionization-recorder" of Wait and 
McNish (Monthly Weather Review, vol. 62, 
pp. 1-4, 1934), was constructed in the instru- 
ment-shop, and calibrated and tested, so far 
as time permitted, by Sherman and Gish; and, 
since this could not be completed before Dr. 
Zies, who was to use it, left for Guatemala, 
a description and directions for its use were 
written. The ionization-chamber is in the 
form of a circular cylinder about 36 cm long 
and 22 cm in diameter. The cylindrical wall 
consists of cellophane, about 0.025 mm thick, 
supported on an open-mesh brass screen. A 
considerable proportion of the alpha rays 
from the radioactive matter in the outside 
air can pass through this wall and produce 
ions inside the chamber. Tests in the labora- 
tory indicated that of the total ionization 
inside the chamber (about 15 ion-pairs per 
cubic centimeter per second), 22 per cent was 
due to alpha radiation coming from radio- 
active matter in the air outside, the rest being 
due to gamma radiation, chiefly from radio- 
active matter in the Earth, to cosmic radia- 
tion, and to an undetermined but probably 
small "residual ionization" caused by radia- 
tions from radioactive impurities contained 
in the materials from which the walls of the 
chamber are made. Below the ionization- 
chamber is the electrometer used in measur- 
ing the charge given, by the ions collected, 
to an insulated rod which stands along the 
axis of the ionization-chamber. Below the 
electrometer is a compartment for batteries, 
switches, etc. These parts are all rigidly 
joined together into a unit with over-all 
height of 73 cm which fits into a cylindrical 
metal carrying and protecting case of about 
the same height and about 26 cm diameter. 
If in part of the measurements this case is 
left in place around the ionization-chamber, 
the alpha rays from outside are absorbed by 
it so that then only the ionization due to 
gamma rays, cosmic radiation, and the resid- 



7 6 



CARNEGIE INSTITUTION OF WASHINGTON 



ual ionization are measured. (Ionization 
from beta rays in the atmosphere is estimated 
to be only about 3 per cent of the total.) The 
difference between measurements made in 
this way and those made with the case com- 
pletely removed is then a measure of the part 
attributable to alpha rays. According to esti- 
mates made by Professor V. F. Hess, of Ford- 
ham University, alpha rays produce about 
92 per cent of that part of the ionization 
which depends upon radioactive matter in the 
air, and gamma radiation produces about 97 
per cent of that attributable to radioactive 
matter in the Earth. On the basis of these 
estimates it is expected that from a survey 
which can be made with this apparatus it 
should be possible to obtain worth-while in- 
formation about the relative distribution of 
radioactive matter both in the air and in the 
Earth near the surface. 

Several visits to the Department during the 
year by Professor Hess were occasions for 
conferences which were particularly stimu- 
lating because of his years of active interest 
in problems of atmospheric electricity. Ar- 
rangements were made for effecting some 
improvements in two nuclei-counters, belong- 
ing to him, by an outside instrument-maker 
working in our shop under the supervision 
of Steiner. These were then tested and com- 
pared with DTM counter no. 6 by Sherman. 
Nathan Cornfeld, a graduate student with 
Professor Hess and instructor in physics at 
Long Island University, conferred twice dur- 
ing the year with members of the staff regard- 
ing an investigation of condensation-nuclei in 
the atmosphere which he has undertaken 
under the direction of Hess. 

An ionium-coated "collector" was supplied 
to Professor H. T. Stetson, of Massachusetts 
Institute of Technology, for use in measure- 
ments of the potential-gradient in the at- 
mosphere. 

Gish served on the Subcommittee on Light- 
ning Hazards to Aircraft, of the National 
Advisory Committee on Aeronautics. 

Geoelectricity 

Work pertaining to the electrical phe- 
nomena in the Earth was confined chiefly to 



examinations for controlling the operations 
at the observatories, making final check and 
reductions of tabulations of these as received, 
and in general putting these in form suitable 
for further investigation and for publication 
(Rooney). Two papers, one on "Initial geo- 
electric work at volcano Santa Maria" (Gish), 
the other on "Variation in earth-current 
activity with sunspot-cycle" (Rooney), were 
completed for publication and presented at 
the Washington meeting of the International 
Union of Geodesy and Geophysics. The sub- 
stance of these was reported last year. 

Resistivity-survey at Quezaltenango, Guate- 
mala. In connection with the extensive vol- 
canological investigation which the Institution 
has supported and carried on for several years 
in Guatemala, the Department in cooperation 
with the Geophysical Laboratory undertook 
a series of earth-resistivity measurements to 
determine the probable depth of the extensive 
deposits of volcanic ash on the upland plains 
of that country. The main survey was made 
on the plain just north and east of the city 
of Quezaltenango, approximately 1 1 km from 
the volcano Santa Maria. The survey covered 
an area of about 30 square km, on which 
20 lines, mostly 1200 m long, were run, thus 
securing records of the average resistivity to 
depths of 400 m (1300 feet). 

The surface-soil of this plain consisted al- 
most exclusively of fine pumiceous material, 
and the object of the investigation was to 
determine, if possible, the depth of these 
deposits. Measurements of the specific resist- 
ance of the ash made at a dozen or more 
stations in road-cuts or on natural escarp- 
ments showed that, like most overburden 
materials, its resistance depends almost en- 
tirely on the amount of moisture it contains. 
At stations near to, and practically at the same 
level as, the Samala River, two branches of 
which follow tortuous courses through the 
plain, the recorded values of resistivity re- 
mained fairly constant at between 4000 and 
6000 ohm-cm, regardless of the electrode- 
separation or depth of soil included, down to 
the maximum depths of 300 or 400 m. This 
value, then, is undoubtedly representative for 
the volcanic ash when wet. 



DEPARTMENT OF TERRESTRIAL MAGNETISM 



77 



At all other stations the recorded resistivity- 
values, starting rather low because of a super- 
ficial layer of moist arable soil, increased 
sharply with depth as more and more dry ash 
was included in the measurements, until the 
underground water-level was reached. This 
occurred at a depth of anywhere from a few 
meters to ioo m or more, depending on the 
location and elevation of the station. Follow- 
ing the maximum point on the curve, which 
corresponds to the underground water-level, 
the recorded values showed a slow and steady 
decrease toward the values recorded in the 
river-bottom. At no place, except possibly at 
one or two stations near the edges of the plain 
where topographical irregularities make the 
interpretation of the results somewhat uncer- 
tain, was there any indication of a definite 
change in structure to depths of 400 meters. 
At one station in the center of the plain the 
measurements were extended to depths of 500 
and 600 m (1640 to 1970 feet) without any 
change in the general trend of the results. 

Practically no information is available 
about the structure underlying the ash. It is, 
however, almost certain that a change of 
structure from the well-moistened ash to a 
dense igneous rock or even a well-consolidated 
sedimentary should have been revealed by a 
second change in the trend of the recorded 
values. It must therefore be concluded either 



that the ash-deposits are thicker than the 
depths to which the measurements were ex- 
tended, 400 m in most cases, or, as is some- 
what less likely, that the underlying rock is 
unusually porous and has practically the same 
resistivity as the wet overburden. 

A notable feature of the survey was the 
uniformity of the results over most of the area 
surveyed. Aside from the shift in the position 
of the maximum point, which in a number 
of instances could be readily correlated with 
the underground water-level by reference to 
near-by wells, all the curves obtained on the 
flat central section of the plain were almost 
identical. 

Publications 

Publications during the report-year relating 
to terrestrial electricity are listed in the 
bibliography at the end of this report. The 
following papers (not yet published) were 
presented at the annual meeting of the Ameri- 
can Geophysical Union in 1940: "Distribu- 
tion of electric elements in the air near the 
Earth's surface," by O. H. Gish; "Total and 
uncharged nuclei at Washington, D. C.," by 
K. L. Sherman. G. R. Wait and O. W. Torre- 
son, at the Washington meeting of the 
American Physical Society in April 1940, gave 
a paper on "Recombination of ions from gas 
flames." 



INVESTIGATIONS OF THE IONOSPHERE AND ITS RELATION TO 
PROBLEMS OF TERRESTRIAL MAGNETISM 



Ionospheric investigations of the Depart- 
ment are directed toward disclosure of funda- 
mental relations between electrical conditions 
in the Earth's outer atmosphere and geomag- 
netic changes which arise there. It is known 
from the fundamental theoretical work of 
Gauss, as extended by Stewart and Schuster, 
that ephemeral changes in geomagnetism 
must have their origin, in part at least, in the 
outer atmosphere. Direct investigation of 
outer atmospheric regions by radio methods, 
initiated by the Department in 1925, has 
demonstrated experimentally the existence of 
ionized layers of a nature that could account 



for certain of the geomagnetic fluctuations. 
The character of these highly ionized re- 
gions, however, has been found to be much 
more complicated than was originally sup- 
posed, with three major ionized strata in 
evidence. The problem has therefore resolved 
itself into a careful examination and analysis 
of the nature of each of these regions in order 
that the origin of geomagnetic fluctuations 
may be localized and examined quantitatively 
and their sources disclosed. 

Besides their purely geomagnetic signifi- 
cance, the ionospheric investigations of the 
Department have collateral importance to 



78 



CARNEGIE INSTITUTION OF WASHINGTON 



other fields of science and to radio communi- 
cation. Since radio wave-transmission over 
great distances depends upon reflection of 
radio waves from the ionosphere, detailed 
definition of ionospheric structure and varia- 
tion is of fundamental importance to this 
phase of communications engineering; infor- 
mation of this kind is now being obtained. 
Furthermore, ionospheric measurements bid 
fair to yield a new and more accurate index 
for measuring variations in solar radiation 
than has been available heretofore; this pro- 
vides a new tool for study of the physics of 
the Sun. The investigations have also pro- 
vided a tool for attack on certain problems of 
pure physics. 

The ionization of the Earth's outer atmos- 
phere is produced chiefly by emanations from 
the Sun. These can be divided into two 
classifications, namely, (i) ultraviolet ioniz- 
ing radiation traveling toward the Earth at 
the velocity of light, and (2) corpuscular radi- 
ation probably consisting of atoms or mole- 
cules traveling at a considerably lower velocity 
than that of light because of their relatively 
great rest-mass. There is also the possibility of 
ionization by streams of corpuscular radiation 
not originating from the Sun, but bombard- 
ing the Earth as it intersects these moving 
streams in space. Radiations such as stellar 
ultraviolet and cosmic rays can account per- 
haps for only 1 or 2 per cent of the observed 
ionization. One of the great problems of 
ionospheric investigation is to determine the 
relative amount and importance of these 
sources, both corpuscular and ultraviolet, and 
to determine the character of the corpuscular 
radiation. 

Probably the greatest forward step in the 
investigations has been the development by 
the Department of an apparatus for continu- 
ous recording of ionospheric structure. As 
described in previous annual reports, this has 
made possible the collection of continuous 
data concerning ionospheric changes at several 
locations, in particular at the Department's 
two magnetic observatories, from which we 
have the longest series of continuous iono- 
spheric data anywhere obtainable (Huancayo 
Magnetic Observatory since 1937 and 



Watheroo Magnetic Observatory since 1938). 
It is planned to extend the work over a sun- 
spot-cycle, so that the principal characteristics 
of the ionized regions may be quantitatively 
defined through a wide range of solar 
changes. These data are proving invaluable 
not only in providing information for solu- 
tion of the problems at hand, but also in dis- 
closing many new factors heretofore un- 
recognized. 

Previous reports of ionospheric investiga- 
tions at the Watheroo and Huancayo mag- 
netic observatories, taken together with the 
work of investigators in the northern hemi- 
sphere, have served to delineate qualitatively 
the world-wide features of ion-distribution in 
the outer atmosphere. Work reported last 
year indicated certain fluctuations in ion- 
density which may be purely local in char- 
acter, as contrasted with the more universal 
variations. These fluctuations have been 
given further detailed attention during the 
past year — an emphasis which was made 
possible by the availability of the continuous 
homogeneous data from the observatories. In 
particular, methods of separating universal 
variations from those of purely local character 
have been investigated in order that the 
origin of each kind of fluctuation may be 
determined. 

Principal Investigations 

Origin of ionospheric fluctuations. The 
solution of this important problem depends 
primarily upon analysis of data from suitable 
locations such that the observed variation can 
be broken down into simple fluctuations aris- 
ing from individual sources. Solution of the 
problem is contingent upon availability of 
continuous data for analysis. Operations of 
recording apparatus at the magnetic observa- 
tories of the Department are fulfilling this 
need. 

Analysis of the F 2 -region of the ionosphere 
has shown that over the period of a year there 
are three major changes: (1) a seasonal 
change, with the maximum of ion-density 
occurring near midwinter in both northern 
and southern hemispheres, the time of maxi- 
mum differing by 6 months between the two 



DEPARTMENT OF TERRESTRIAL MAGNETISM 



79 



hemispheres; (2) an annual change, having a 
maximum about January in both hemispheres, 
the source of which is not understood; and 
(3) a change with sunspot-number, which 
appears to go through a complete cycle in 
phase with the sunspot-cycle. All these are 
major variations and when combined deter- 
mine the average ion-density at a particular 
location. Superimposed on this average are 
daily and other short-period variations which 
change in magnitude according to the time 
of year, latitude, sunspot-number, and char- 
acter of simultaneous magnetic activity. The 
extent to which the magnitude and character 
of daily variations are related at two stations 
on a particular day must be evaluated in 
determining the origin of such variations. 

Investigations during the past year show 
that fluctuations of ion-density with magnetic 
activity are evident at both Huancayo and 
Watheroo for even very small magnetic 
activity, as low as index 1 on the scale of 
to 9 of the ^T-index of geomagnetic dis- 
turbance. The nature of the ionospheric 
disturbance is not the same at both observa- 
tories. At Huancayo the average ion-density 
taken over the day rises steadily as magnetic 
activity increases, until limited by unusually 
severe disturbances, when the F 2 -region 
simply "blows up" and disappears, as de- 
scribed later in this report. At Watheroo the 
relation between ionization and geomagnetic 
activity changes with season. During the 
summer the ion-density falls steadily with 
increasing geomagnetic activity. During the 
winter the ion-density rises, as at Huancayo, 
until moderate geomagnetic disturbances are 
observed, and then falls rapidly with increased 
disturbance in much the same way as in 
summer. Thus fluctuations from day to day 
at the two observatories are related in a com- 
plicated way through association with geo- 
magnetic activity. During the summer the 
relationship is inverse for all but the severest 
geomagnetic disturbances; during the winter, 
however, the relationship is direct for moder- 
ate, and inverse for the more severe geo- 
magnetic disturbances. The pattern at Wash- 
ington is similar seasonally to that at 
Watheroo. 



The amplitude of diurnal variation changes 
with season and with sunspot-number at both 
stations. After correction for difference in 
latitude, and after removal of these variations, 
there remains a large irregular fluctuation in 
ion-density which does not appear common 
to both stations. The question is whether 
this is local in character or is caused by rapid 
change in the solar ionizing radiation as the 
Earth rotates from noon at Huancayo to noon 
at Watheroo — in time, about one-half day. 
To answer this question, automatic multi- 
frequency recorder no. 3 was constructed and 
installed at the Experimental Station of the 
Department at Kensington, Maryland (near 
Washington, D. C). This recorder provides 
data for direct comparison with Huancayo. 
Since Huancayo and Kensington are on the 
same meridian, noon occurs nearly simul- 
taneously at both stations; therefore, changes 
in ionization arising from changes in solar 
radiation should be common to both stations. 
Thus, as data become available from this 
third station, it should be possible to identify 
more exactly that portion of the change in 
diurnal variation of ion-density for which the 
Sun is directly responsible and that portion 
which is of local origin. The data should also 
afford valuable collateral evidence to aid in 
identifying the cause of the annual effect. 

The possibility that local variations of ion- 
density of large magnitude may occur raises 
some interesting problems. The question may 
be asked whether such local fluctuations could 
arise from meteorological influences. Meteor- 
ologists heretofore have thought that atmos- 
pheric movements were confined entirely to 
the lower atmosphere, with the outer atmos- 
phere entirely quiescent. The recent work of 
Martyn and his associates shows that further 
investigation of this point is desirable to deter- 
mine whether or not any relation exists be- 
tween meteorology of the lower and of the 
outer atmosphere. 

E-region investigations. Evidence obtained 
during radio fade-outs (see annual reports in 
Year Books Nos. 36-38) has demonstrated 
that electrical currents flowing at levels be- 
tween 60 and 100 km are probably responsible 
for the daily changes in geomagnetism. It 



8o 



CARNEGIE INSTITUTION OF WASHINGTON 



appears that within this region of the atmos- 
phere much of the solar influence is translated 
into geomagnetic effect. Detailed investiga- 
tion of this region would therefore be fruitful 
and is under way. 

Four lines of effort seem promising, espe- 
cially with regard to changes during the day, 
with latitude, with season, and with variation 
of solar radiation. These lines are: (i) com- 
parison of continuous observations of E-region 
ion-density at different locations with existing 
theories to determine the adequacies or defi- 
ciencies of the theories; (2) investigation of 
special conditions during eclipse of the Sun; 
(3) critical experimental investigation of 
change of ion-density with height and time 
of day for comparison with theoretical pre- 
dictions; and (4) determination of conduc- 
tivity with respect to height. This program 
should ultimately lead to an exact quantitative 
theory for the E-region from which condi- 
tions at any location may be satisfactorily 
predicted. Research on the first two lines is 
under way and plans for the third and fourth 
are under consideration. 

Examination of maximum ion-density at 
Washington, Watheroo, and Huancayo shows 
that daily changes are not satisfactorily pre- 
dicted by existing theory. Though deviations 
from theoretical values are not more than 20 
to 30 per cent, they are in a direction which 
cannot be explained by the theory in its 
present form. For instance, the rate of de- 
crease of ion-density in the afternoon is 
greater" than would be expected from theory, 
using infinite values of recombination-coeffi- 
cient. Earlier measurements did not direct 
attention forcefully to these discrepancies be- 
cause ion-density was measured down only 
to about one-fourth the maximum value. 
Measurements of ion-densities with the more 
modern and complete equipment at the ob- 
servatories carry down to about 1 per cent of 
maximum values; these make the discrepan- 
cies quite apparent. It is clear, therefore, that 
further theoretical work must be done to 
reconcile theory and experiment. This por- 
tion of the investigation is along two lines, 
namely, (1) compilation of experimental data 
to facilitate theoretical investigation and (2) 



study of factors in the theory, hitherto 
neglected, which must be taken into account 
to obtain agreement. Observations during 
solar eclipses are especially useful for deter- 
mining values to be used in the theory. The 
rapid changes during eclipses permit more 
accurate determination of such factors as 
recombination-coefficient than is possible un- 
der ordinary conditions. 

Observations were made during the solar 
eclipse of April 7, 1940, at the Kensington 
Experimental Station, where the eclipse 
reached 73 per cent totality. During the early 
stages of the eclipse maximum ion-density 
decreased more rapidly than was predicted 
from normal-day conditions. This would 
indicate that the Sun is not giving out the 
ultraviolet ionizing radiation uniformly from 
every part of its surface. It appears that dur- 
ing the early stages of the eclipse one of the 
more active portions of the Sun's surface was 
covered so that the production of ionization 
was decreased more quickly than would have 
been expected from a uniformly radiating sur- 
face. Observations of both E- and ivregions 
confirm this view. 

Plans were perfected and arrangements 
were made for similar observations at the 
Huancayo Magnetic Observatory during the 
solar eclipse of October 1, 1940. Here the 
Sun will rise almost totally eclipsed, so that 
especially valuable information concerning 
conditions at sunrise is expected. For these 
observations the standard multifrequency 
observations are made at about three times 
normal speed, so that a complete set of obser- 
vations is available at intervals of about five 
minutes. 

Plans have been made for precise measure- 
ments of height-variation of the E-layer. This 
requires a new technique involving the inter- 
ference of the transmitted wave and the wave 
reflected from the ionosphere. Success of this 
method should permit measurements , of 
height-changes of a few meters, an accuracy 
required because of the small changes in 
height experienced in the E-region. 

Ionospheric changes during great magnetic 
storms. Continuous ionospheric observations 
through the recent maximum of solar and 



DEPARTMENT OF TERRESTRIAL MAGNETISM 



geomagnetic activity have made possible de- 
lineation of ionospheric changes during the 
magnetic disturbances associated with this 
maximum. The great disturbance on Easter 
Sunday, March 24, 1940, was probably the 
most violent magnetic storm yet observed. At 
the beginning of this disturbance at the Huan- 
cayo Magnetic Observatory the F 2 -region of 
the ionosphere rose rapidly in height at a 
velocity one-third to one-half of the velocity 
of sound. As the height increased the ion- 
density decreased. At the end of 30 minutes 
the ion-density had diminished to less than 
20 per cent of its original value and ionization 
in the F 2 -region could be observed only at 
great heights, of the order of 1000 km. The 
event appeared to be a sort of gigantic explo- 
sion of the outer atmosphere above levels of 
250 to 300 km. As the F 2 -region of the pre- 
storm epoch was rapidly disappearing up- 
ward, a new F 2 -region was formed in place 
of the old, probably because of the continued 
incidence of ultraviolet light. This new re- 
gion formed rapidly and provided informa- 
tion which made possible calculation of the 
rate of production of ionization in the F 2 - 
region — a calculation practically independent 
of any theory of F 2 -region variation. It is as 
though the Sun were suddenly "turned on" 
after rising over an un-ionized atmosphere, 
ionizing it during an interval over which no 
material change of solar zenith-distance oc- 
curred. Ionospheric disturbances of this kind 
are extremely rare, as are the great geo- 
magnetic disturbances associated with them. 
One such disturbance occurred on April 16, 
1938, and was reported last year (see Year 
Book No. 38). The general pattern of move- 
ment of the ionosphere was the same at 
Huancayo during both disturbances. This 
earlier disturbance took place at night at 
Huancayo, so that the Easter disturbance 
remains unique in so far as data are available 
for basic computations of quantity of ionizing 
radiation. 

Study of radio fade-outs. The time and 
intensity of radio fade-outs, given by iono- 
spheric records, provide investigators of mag- 
netic phenomena with data on fade-outs pre- 
ceding major magnetic disturbances. From 



these the geomagnetician can calculate the 
velocities of corpuscular streams thought to 
emanate from active solar areas and thought 
to be responsible, as these streams envelop 
the Earth, for magnetic disturbances. 

Relation between actual and virtual iono- 
spheric height. Ionospheric records result 
from successive measurements of height for 
successive values of ion-density. The curves 
so formed photographically in the recorder 
show in effect a graph of ion-density versus 
"virtual" height. The curves are in terms of 
virtual rather than actual height because the 
exploring wave travels at a reduced velocity 
in the ionized regions. The virtual height, 
therefore, is always greater than the actual 
height by an amount which depends upon 
the density and distribution of ionization 
through which the wave has passed in reach- 
ing the point at which it is turned back. Re- 
duction of virtual to actual height has been 
one of the most troublesome problems. 
Generally the equations are so complex that 
the reduction to actual height could be made 
practically for only a very few ionospheric 
records. 

To meet this situation, a simple method of 
determining actual height of ionization has 
been developed which is readily applicable 
to most records. Virtual heights of the iono- 
sphere are translated to actual heights by 
fitting a parabolic maximum of electron- 
density to observations of variation of virtual 
height with wave-frequency. The simplest 
measure of actual height of maximum elec- 
tron-density is the virtual height at five-sixths 
of the penetration-frequency. This measure 
is found to be remarkably reliable for the 
F-region at night; other indices for deter- 
mination of height and thickness of the 
layers can also be applied with equal relia- 
bility. During the daytime it is often neces- 
sary to correct Fx-observations for presence of 
F-region, and F 2 -observations for presence of 
Fx-region. A simple technique for this cor- 
rection has been developed. 

Application of the new technique to a large 
number of records shows that the actual layer- 
distribution can be successfully represented 
as a parabolic distribution with ample accu- 



82 



CARNEGIE INSTITUTION OF WASHINGTON 



racy for most purposes. It appears doubtful 
whether more detailed and laborious compu- 
tations yield a very much better result. 

The parabolic distribution can be repre- 
sented easily and exactly by two simple num- 
bers, namely, the maximum ion-density and 
the semi-thickness of the layer. Thus the 
representation of each layer is greatly simpli- 
fied for purposes of mass-analysis of data for 
the many variables involved. 

Maximum usable frequency for long- 
distance communication. The relation be- 
tween the maximum usable frequency for 
long-distance communication and the pene- 
tration-frequency of the layer at vertical inci- 
dence depends upon whether the Sellmeyer 
or the Lorentz theory is employed. Analytical 
expressions for the ratio of these two fre- 
quencies on both theories have been obtained 
taking into account the curvature of the 
Earth. For a given penetration-frequency at 
vertical incidence, the maximum usable fre- 
quency for long-distance communication is 
greater for the Lorentz theory than for the 
Sellmeyer theory by a factor V3/2. It has 
been suggested that this effect would be 
marked by the fact that the parabolic maxi- 
mum of electron-density required to fit the 
variation of virtual height with wave-fre- 
quency observed at vertical incidence would 
depend on whether the Sellmeyer or the 
Lorentz theory is used. It turns out, however, 
that this is not the case. Observations so far 
made of the relation between maximum 
usable frequency and penetration-frequency 
favor the Lorentz theory, but are not con- 
clusive. 

Scattering of waves from the ionosphere. 
Waves scattered back to the transmitter from 
the Earth via the layer would form on an 
automatic multifrequency record a blurred 
trace having a sharp lower edge of the follow- 
ing type: Let ABC be the curve of the second 
multiple reflection at vertical incidence, 
drawn on a linear frequency-scale. Let O be 
the point corresponding to zero virtual height 
and zero frequency. From O draw a tangent 
to ABC touching it at B. Produce OB indefi- 
nitely to D. Then, on the Sellmeyer theory, 
the lower edge of the scattered trace is given 



by the curve ABD. On the Lorentz theory, 
the portion BD would be slightly curved. An 
echo of this type is quite common on auto- 
matic multifrequency records. 

In the above investigations the effect of the 
Earth's magnetic field has been neglected. 
Progress has, however, been made with the 
theory of propagation of waves through a 
horizontally stratified ionosphere taking into 
account the Earth's magnetic field. Curves 
for a series of typical cases of oblique inci- 
dence have been plotted. 

Polarization of downcoming waves. Deter- 
mination of the state of polarization of the 
downcoming waves from the ionosphere 
forms one of the most rigorous experimental 
methods of testing the theory of propagation. 
Theory predicts that at the Huancayo Mag- 
netic Observatory waves reflected from over- 
head should be plane polarized, and earlier 
work at Huancayo on the F 2 -region using 
manual step-by-step methods has shown this 
to be correct. These experiments were re- 
peated with modern equipment and a rotat- 
able antenna. The results of the original 
experiments have been confirmed and their 
general applicability to all regions of the 
ionosphere has been extended. The theory 
from which ion-density is computed must 
now be generally accepted as meeting all the 
observed facts, the only quantity remaining 
in doubt being the value of the Lorentz 
polarization-correction (see report of last 
year). 

Recording and Discussion of Data 

Recording of data. The use of automatic 
multifrequency apparatus for continuous re- 
cording of ionospheric conditions was con- 
tinued throughout the year at both the Huan- 
cayo and Watheroo magnetic observatories. 
The success of this program is to be credited 
largely to the staffs of the observatories, 
whose careful supervision of the relatively 
complex apparatus has made possible a prac- 
tically homogeneous series of records with 
negligible loss of traces because of mechanical 
or electrical failures. Continuous records of 
the third apparatus, at the Kensington Experi- 



DEPARTMENT OF TERRESTRIAL MAGNETISM 



83 



mental Station, have been obtained from early 
in April 1940. After one year's operation at 
Kensington this apparatus will be available 
for field-work. 

Standardization of recording technique — 
an important factor in simplifying operation 
— has become possible with the accumulation 
of experience in the field. As a result, ob- 
servers can now be trained in procedures for 
maintenance and calibration before assign- 
ment to the observatories. 

Tabulation and publication of data. Nine 
sheets of scalings from the records are pre- 
pared monthly at each observatory. On these 
are tabulated the hourly values of minimum 
virtual heights and heights of maximum ion- 
density of the F x - and F 2 -regions, penetration- 
frequencies of the E-, Fi-, and F 2 -regions, 
minimum wave-frequency at which reflections 
occur, and the squares of the F 2 penetration- 
frequency. Daily means and hourly values of 
monthly means are computed on each sheet. 
The mean data for each month are published 
in the Journal of Terrestrial Magnetism and 
Atmospheric Electricity , and thus made avail- 
able to investigators at the earliest possible 
date. Annual averages are published at the 
end of each year. Tabulations of sporadic 
F-region ionization at Watheroo have been 
discontinued, as it has become evident from 
experience that such investigations will re- 
quire a more complex analysis than can be 
given in the time available at the Observatory. 
Radio fade-outs, which are occurring with 
diminished frequency as sunspot-activity de- 
creases, are tabulated monthly. 

Harmonic analysis of data. Harmonic 
analysis of the jF 2 -region data, for detailed 
study of variations of ionization, is made at 
the Department directly from the hourly 
tabulations compiled at the observatories. For 
analysis of maximum values of the F 2 -region 
ionization, a 12-ordinate system is used and 
harmonic coefficients for the first five har- 
monics are derived. Harmonic analysis of 
these data is practically completed through 
1939 for both observatories. Harmonic analy- 
sis of minimum virtual height at both observa- 
tories has been made for 1938 and part of 



1939, to permit study of the usefulness of 
this type of analysis for the height data. 

Personnel. The program of ionospheric in- 
vestigation was maintained by Berkner and 
Seaton at Washington and Wells at Huan- 
cayo, together with Booker as Research As- 
sociate at Washington and at Cambridge, 
England. Aid in computations was given by 
Niepold and Jones, and Ledig assisted at the 
Kensington Experimental Station. The staffs 
at the observatories supervised and main- 
tained the equipment at the observatories. 

Cooperative Endeavors 

Sixth Conference on Ionospheric Research. 
The Sixth Annual Conference on Ionospheric 
Research was held in the library of the De- 
partment of Terrestrial Magnetism on April 
27, 1940, under the chairmanship of Dr. O. R. 
Wulf, of the U. S. Weather Bureau. It was 
attended by forty-one persons, representing 
the following organizations interested in iono- 
spheric research: Bell Telephone Labora- 
tories; Department of Terrestrial Magnetism, 
Carnegie Institution of Washington; R. C. A. 
Communications; Jansky and Bailey; Signal 
Corps, U. S. Army; Harvard University; 
Q S T Technical Staff; National Bureau of 
Standards; U. S. Coast and Geodetic Survey; 
Naval Research Laboratory; Federal Com- 
munications Commission; U. S. Weather 
Bureau; Gulf Research and Development 
Company; University of Rochester. 

The importance of purely scientific research 
in terrestrial magnetism was emphasized by 
discussions at the Conference. Conversely, 
experience derived from commercial radio 
communication was shown to have important 
bearings on scientific knowledge of geo- 
magnetism. As at previous conferences, the 
greatest interest was evoked by discussions 
of magnetic storms and their association with 
marked changes in conditions of transmission. 
The discussion indicated the development of 
various widely different lines of research dur- 
ing the past year. Improved methods of 
evaluating transmission-disturbance, and ap- 
plication of the new range-index K for meas- 
uring magnetic activity to problems of com- 



CARNEGIE INSTITUTION OF WASHINGTON 



munication, were discussed in some detail, as 
was comparison of work on many other iono- 
spheric and wave-propagation problems. 

Papers or lectures were given by members 
of the Department before a number of scien- 
tific and other organizations, including the 
Association of Terrestrial Magnetism and 
Electricity of the International Union of Geod- 
esy and Geophysics, Philosophical Society of 
Washington, International Scientific Radio 
Union, Institute of Radio Engineers, Wash- 
ington Radio Club, and Section on Physics 
of the Eighth American Scientific Congress. 
The Department was represented at the 
annual conventions of the Institute of Radio 
Engineers and the American Institute of 
Electrical Engineers. The Carnegie Institu- 
tion of Washington was represented on the 
Executive Committee of the International 



Scientific Radio Union, on the Wave-Propa- 
gation Committee of the Institute of Radio 
Engineers, and on the Joint Committee for 
Ionospheric Research, Association of Terres- 
trial Magnetism and Electricity of the Inter- 
national Union of Geodesy and Geophysics, 
by Berkner. Because solution of problems of 
ionospheric research requires widespread dis- 
tribution of stations over the Earth to eluci- 
date the detail of world-wide ion-distribution, 
the Department maintains close cooperation 
with other organizations doing ionospheric 
research throughout the world. In many cases 
it has been possible to assist other organiza- 
tions in the development of apparatus and 
in the interpretation of data. Conversely, the 
information obtained through close cooper- 
ation with other organizations has been help- 
ful in the development of problems. 



MAGNETISM AND ATOMIC PHYSICS 



Interactions of the Primary 
Material Particles 

The existence of a new type of interaction 
between material things, namely, the intense 
short-range forces between the protons and 
neutrons which form the nuclei of all atoms, 
has been amply confirmed during the past 
several years. These nuclear forces are funda- 
mental in the same sense that gravitational 
and electromagnetic forces are fundamental: 
all three are universal in Nature; they cannot 
be derived from one another, but all known 
forces or interactions between material bodies 
can be described in terms of them. It is not 
inconceivable that a connection of some kind 
exists between these fundamental forces, and 
indeed experimental evidence has been 
sought, for example, for effects of nuclear 
forces on electrons, which are presumed to 
be simply electric charges with magnetic 
moment but without associated nonelectrical 
mass. The fact that the neutron has a mag- 
netic moment and exhibits the same nuclear- 
force properties as the proton, although it 
has no electrical charge, also indicates the 
possibility of ultimately finding a relationship 
of some kind. To illuminate these funda- 



mental questions concerning the nature of 
magnetism and its role in the intimate struc- 
ture of matter, experiments which reveal the 
action of electrical, magnetic, and nuclear 
forces in various cases of close interaction 
between primary particles, limited to the 
simplest cases of a few particles to permit 
detailed analysis, are being formulated and 
made. 

The measurements on the proton-proton 
interaction at the Department three years ago 
have been confirmed and extended by other 
workers. Further deductions regarding this 
type of pair-forces can best be made by 
utilizing protons accelerated through poten- 
tials of the order of 5,000,000 volts or even 
higher. The construction of the Atomic- 
Physics Observatory and its equipment was 
not rewarded with the good fortune of 
immediate attainment of these expected 
voltages. Considerable time was expended by 
the staff, especially Hafstad, Meyer, and 
Heydenburg, on improving the voltage and 
other operating characteristics of this equip- 
ment. Improvement was achieved, the unit 
being made to operate satisfactorily up to 
3,600,000 volts and at times somewhat higher, 
but it seems clear that the original vacuum- 



DEPARTMENT OF TERRESTRIAL MAGNETISM 



85 



tube installed at the end of 1938 must be 
taken down and fitted with new electrodes, 
or that other internal modifications must be 
made, before further improvement is to be 
realized. Failure, by sparking, also occurs 
down the porcelain columns at peak-voltage, 
and some changes in the support-structure 
made this year point in the direction of 
further improvements. An effort is made, 
however, to confine these tests and changes 
to limited time-intervals, permitting the use 
of the equipment for nuclear-physics measure- 
ments and the production of radioactive 
materials during the rest of the time. 

Specific Projects 

Attacks were made on five different prob- 
lems concerned with the forces acting be- 
tween the primary particles. 

Salant and Ramsey concluded an extensive 
series of observations begun last year on the 
scattering of very fast neutrons by collisions 
with protons (hydrogen). They utilized the 
group of 14- to 16-mev neutrons emitted by 
lithium under deuteron bombardment, using 
as a detector an endothermic nuclear reaction 
in copper which does not respond to neutrons 
of lower energy. Their final value for this 
scattering cross-section agrees rather closely 
with the value predicted by a theory which is 
not elaborated to include the deuteron quad- 
rupole moment and other recent features, 
thus setting another limit on the extent to 
which these features may preponderate. 

Van Allen and Ramsey attempted to meas- 
ure the angular distribution of the scattering 
of fast (15-mev) neutrons by protons, using 
a triple-coincidence arrangement of propor- 
tional counters to reduce the background of 
neutron-recoils of lower energy. This attempt 
has not yet been successful, but the observa- 
tions have indicated that the measurement 
may be feasible if certain modifications are 
made. If this angular distribution can be 
obtained, it will be valuable as a measure of 
the energy-region in which unsymmetrical 
interactions of higher order become important 
in scattering. This region has not yet been 
determined for either the proton-proton or 
the proton-neutron interaction, and knowl- 



edge of these higher-order interactions seems 
essential to a further development of our 
understanding of the nuclear forces. A current 
question, for example, is whether the nuclear 
forces arise from the interaction of mesons 
(heavy electrons) with the massive nuclear 
particles. 

An experiment in connection with the dif- 
ference between the interaction of a proton 
with a group of nuclear particles and that of 
a neutron with the same group was made by 
Ramsey and Heydenburg. In addition to the 
difference arising primarily from the charge 
on the proton, other differences exist, even 
though the masses of these two particles are 
nearly alike and the measured proton-proton 
and proton-neutron pair-interactions are prac- 
tically equal when correction is made for the 
electrostatic forces. For example, the magnetic 
moment of the proton is more than twice that 
of the neutron. The convenient analytical 
approach of treating the interaction of an 
added particle as that of a single unit inter- 
acting with the averaged effect of the group, 
used in treating the outer parts of an atom, 
cannot be relied upon for the nucleus, since 
the particles are so close together and each 
interacts with every other one simultaneously. 
This is a many-body problem which in 
general is insoluble, and it is accordingly 
important to learn how nearly the single- 
particle picture fits experimental behavior in 
various typical cases. A resonance-effect in 
the collision cross-section for neutrons in 
helium was observed elsewhere two years ago, 
the collision-area being increased by a factor 
of about 5 for neutrons in a narrow band of 
velocities in the region around 1 mev. It was 
of interest to see whether a related resonance 
exists for proton-collisions in helium, at a 
somewhat higher voltage (velocity) to com- 
pensate for the electrostatic repulsion experi- 
enced by the proton approaching the helium 
nucleus. The experimental observations car- 
ried from 1.0 to 3.1 mev showed a proton- 
resonance, but by comparison it was very 
broad and shallow, extending roughly from 
1.5 to 2.5 mev, with an increase of collision- 
area of at most 50 per cent for certain angles. 
Theoretical examination shows this difference 



CARNEGIE INSTITUTION OF WASHINGTON 



to be understandable because of centrifugal 
forces and the charge on the proton. Various 
details of this scattering were examined with 
particular reference to higher orders of 
waves (interactions with different angular 
momenta). 

The target-area for collisions between neu- 
trons and protons is large for neutrons which 
have been slowed down to the low velocitv 
corresponding to ordinary thermal agitation, 
and decreases rapidly as the relative velocitv 
is increased. This fact has been explained as 
the resonance-effect of "a virtual level of the 
deuteron," or a quasi-stable state of associa- 
tion of a proton and a neutron. This simple 
theory predicts a definite way in which the 
collision-area should change with velocity, 
being adjusted at the lowest and highest 
velocities to agree with experiment. Rough 
measurements at the Department in 1936 
gave approximate agreement of the observed 
collision-area for neutrons of intermediate 
speed (0.6 mev) with the predicted inter- 
mediate value. This agreement was impor- 
tant because the experimentally determined 
proton-proton interaction had just been found 
to be very nearly the same as the neutron- 
proton interaction corresponding to the 
theory. Measurements last year in another 
laboratory, however, gave a much smaller 
value for the collision-area of medium-speed 
neutrons, throwing the whole question of the 
neutron-proton interaction and its equality 
with the proton-proton reaction into serious 
doubt. The problem was therefore re- 
examined by Salant and Tuve by means of 
an entirely new series of measurements. 
These measurements were much more accu- 
rate than the determinations of 1936 and 
again agreed satisfactorily with the predic- 
tions of the simple theory, although a slight 
deviation is not excluded. In addition, it was 
shown that the observations which had 
thrown doubt on the agreement were in 
error because a method of measurement was 
employed which responded to gamma rays 
as well as neutrons, and rather intense gamma 
rays accompanied the neutrons used. 

A question which is basic in all considera- 
tions regarding atomic nuclei is that of the 



role of the lighter particles, electrons, or 
mesons (heavy electrons) inside the nucleus. 
To what extent may a proton be considered 
as a combination of a neutron and a positive 
electron? Early attempts at understanding 
the binding forces which hold protons and 
neutrons together as a nucleus pictured an 
exchange of the positive charge between two 
neutrons, effectively combining proton and 
neutron. The theory failed to predict cor- 
rectly various facts, such as the half-life of 
beta-ray emitting nuclei; and the demonstra- 
tion of a proton-proton attraction led to the 
current theories which relate nuclear forces 
to the exchange of mesons between nuclear 
particles. These theories are in an unsatis- 
factory state, and further experimental infor- 
mation is needed. Mesons are observed in 
cosmic-ray studies, but are not under control 
and are not available in the numbers needed 
for studies of their nuclear interactions. 
Electrons have such a small mass that the 
electrostatic effects in or near nuclei are over- 
whelmingly large, even for electrons having 
energies of 5 or 10 mev. An indirect attack 
on the behavior of the electrically charged 
entities in nuclei seems possible, however, by 
careful studies of the effects of high-energy 
electromagnetic radiation (gamma rays) on 
nuclei. Van Allen has made experiments on 
the photo-disintegration of the deuteron into 
a proton and a neutron, using the 6-mev 
gamma rays emitted by fluorine and the 
17-mev gamma rays from lithium, when these 
elements are bombarded by protons. An 
absolute calibration of the numbers of 
gamma-ray quanta emitted in these reactions 
is in progress. 

Uranium Fission 

The possibility that "atomic power" might 
ultimately become available in the form of 
heat evolved from a chain-reaction in ura- 
nium, hypothetically conceivable because the 
splitting or "fission" of a uranium nucleus is 
caused by the capture of a neutron and the 
fission-process is accompanied by the emission 
of free neutrons, was discussed in last year's 
report. Measurements in this connection have 



DEPARTMENT OF TERRESTRIAL MAGNETISM 



87 



been made in many laboratories, and the 
question is still open. At the Department 
special attention has been paid to the target- 
areas for fission-production by fast neutrons, 
and other relevant measurements. An impor- 
tant contribution to the subject was made by 
Abelson. An unknown substance having a 
half-life of 2.3 days was found during 1939 
by Segre in Berkeley. It was not a fission- 
product (non-recoiling), yet the target-area 
for its production was almost as large as for 
fission. During the year it was shown else- 
where that the isotope U 235 is responsible for 
the fissions produced by slow neutrons, and 
a chain-reaction might well be expected if a 
way could be found for separating this isotope 
in large amounts. However, if the 2.3-day 
substance arose also from U 235 , enough neu- 
trons might be consumed by this nonfission 
process to prevent the propagation of a chain. 
Efforts by Abelson and Hafstad to identify 
this substance by experiments using the De- 
partment's equipment were not successful. 
During a recent visit by Abelson to Berkeley, 
however, he and McMillan, of the University 
of California, with the higher neutron-intensi- 
ties available there, succeeded in demonstrat- 
ing that the 2.3-day process arises from ele- 
ment 93 239 . This element originates from 
the isotope U 238 , and hence the considerations 
regarding a possible chain-process using U 235 
are clarified. 

Miscellaneous 

A variety of more or less incidental obser- 
vations and studies were made during the 
year. A search for stable H 3 showed that it 
was not present in amounts as great as io" 12 
of the deuteron-beam from the high-voltage 
tube, indicating that it does not exist as a 
stable isotope, in agreement with the discovery 
of radioactive H 3 . 

Considerable thought and discussion again 
was given to the development of designs for 
an "electron whirlpool," a device having as 
its objective the acceleration of electrons to 
extremely high velocities (in excess of 10 
mev) by utilizing the electric field of a chang- 
ing magnetic field. Numerous measurements 



were made on the yields of various nuclear 
reactions at different voltages, as required for 
current experiments. 

A carefully developed comparison of the 
methods of statistical analysis used in physics 
and geophysics with those used in economics 
and the social sciences was made by Hafstad. 
The methods are mathematically equivalent 
in a broad region of their application, but 
special fields are covered by each type of 
analysis which are not amenable to treatment 
by the other. Neither group of investigators 
seems fully to have realized this fact previ- 
ously, and Hafstad's treatment is likely to 
be of considerable future importance. 

The emergency growing out of violent 
changes in world affairs has led to expendi- 
tures of time and effort in connection with 
national defense which are not described in 
this report. 

Theoretical-Physics Conference 

"The interior of the Earth" was the subject 
of three days of intensive discussion at the 
Sixth Annual Conference on Theoretical 
Physics held in Washington March 21—23, 
1940, under the joint auspices of the George 
Washington University and the Institution. 
A group of 14 investigators in geophysics and 
in theoretical physics from various universities 
in the United States joined a similar number 
of Washington investigators for technical 
examination of some of the outstanding prob- 
lems concerning matter in great bulk and 
under large pressures and temperatures, as 
found inside the Earth. The chief aim of the 
discussions was to formulate these problems 
more clearly for future joint efforts. 

The first meeting was devoted to the pres- 
sure-volume relation at high pressures and 
associated questions concerning the probable 
composition and physical state of the Earth's 
deep interior. For pressures higher than about 
io 8 atmospheres the pressure-volume relation 
can be estimated statistically, and all materials 
must behave in a similar way. At these pres- 
sures the outer electronic shells of the atoms 
are crushed, and in this region the pressure 
increases with the 5/3-power of the density. 



CARNEGIE INSTITUTION OF WASHINGTON 



However, the pressure at the center of the 
Earth reaches a value of only about 3 X io 6 
atmospheres. Some calculations have been 
made for the intermediate region down to 
about io 7 atmospheres, and, interpolating be- 
tween these calculations and the experimental 
data at 20,000 to 50,000 atmospheres, one 
finds agreement with the densities and com- 
pressibilities which geophysicists have de- 
duced for iron in the core of the Earth. As 
one immediate result of these discussions, 
further calculations along similar lines are 
now in progress for the region below 1,000,- 
000 atmospheres. 

The melting point of iron under a pressure 
of 3 X io 6 atmospheres was examined, and the 
calculations indicate a value of 1 0,000 ° K, 
which is somewhat higher than previous esti- 
mates. The evidence from seismology and 
earth-tides which indicates that the deep 
interior of the Earth is in a fluid rather than 
a solid state was discussed, together with 
various considerations bearing on the compo- 
sition and probable stratification of the 
interior. 

Related material of special interest was 
presented by Goranson, who discussed new 
measurements of compressibility extending to 
a pressure above 200,000 atmospheres. 

The main topic of the discussions on the 
second day was the origin and maintenance 
of the great magnetic field of the Earth. 
Beginning with a description of the mag- 
netic moment and its representation by a 
minimum number of internal dipoles, the 
secular variation was discussed and various 
data and calculations were presented with 
regard to the electrical conductivity of the 
Earth at different depths, as inferred from 
the diurnal and magnetic-storm variations. 
Theories of the Earth's magnetic field were 
examined at some length, including recent 
ideas according to which the magnetic effects 
may be due to large thermoelectric currents 
maintained by mass-convection currents in 
the fluid core. Calculations which throw 
some doubt on this theory were put forward 
by members of the Conference; these calcula- 
tions were subsequently published in the 
Physical Review. 



The dynamo-theory in relation to the 
Earth's interior, and the possibility of a ferro- 
magnetic core were discussed. The Confer- 
ence left the Earth's magnetic field as great 
an enigma as before, but evidently resulted 
in an appreciation of its challenge and a 
stimulus to further attack. 

The remainder of the discussions were 
devoted to radioactivity in the Earth and to 
problems of viscosity. 

This Conference had the following objec- 
tives: {a) to formulate the problems and 
data of geophysics which may be of interest 
to workers in theoretical physics; and (b) to 
put at the service of workers in geophysics 
the growing theoretical knowledge concern- 
ing the behavior of matter under unusual 
conditions, especially at very high pressures. 
That this meeting provided an immediate 
basis for further cooperative work has been 
demonstrated, as extended calculations on 
several questions have already been under- 
taken by several theoretical physicists. 

The Cyclotron Program 

An expansion of the Department's activities 
in nuclear physics to embrace an enlarged 
program of fundamental work in biology and 
chemistry, utilizing the artificially radioactive 
isotopes of ordinary elements as tracers for 
following various reactions, was undertaken. 
This program will center around a large 
cyclotron, essentially a duplicate of the 60- 
inch cyclotron installed last year at Berkeley, 
and will involve cooperation with various 
members and groups of the Institution's staff 
working in chemistry and biology, and with 
a number of other research organizations in 
the Washington area, such as the National 
Cancer Institute, the Department of Agri- 
culture and other federal agencies, one or 
more of the local universities, and the Johns 
Hopkins University in Baltimore. In addition 
to the work with radioactive tracers, the 
cyclotron will provide for still further exten- 
sion of the Department's studies of atomic 
nuclei and the primary particles of matter. 

For putting this large project into oper- 
ation, the first necessities were the selection 



DEPARTMENT OF TERRESTRIAL MAGNETISM 



8 9 



of personnel, the design and construction of 
a highly specialized laboratory building, and 
the construction and installation of the cyclo- 
tron itself. Roberts, Abelson, and Green were 
selected to work with Tuve on this project, 
and Cowie was assigned here from the staff 
of the National Cancer Institute. The new 
laboratory is well under way, and many of 
the large parts of the cyclotron are completed 
or under contract for early delivery. It is 
expected that the remaining details of small 
parts, wiring, installation of controls, and 
assembly may be completed by July 1941. 

An important part of the initiation of this 
project, which contemplates the joint activity 
and initiative of investigators in widely sepa- 
rated fields for the broadly defined purpose 
of fundamental research, aside from thera- 
peutic questions, is the development of a 
sound basis for guiding the work with regard 
both to technical and to administrative or 
liaison questions. Actual experience in such 
cooperative work is the only reasonable basis 
for guiding the project as a whole, and ar- 
rangements were made to supplement our 
previous experience by pushing forward a 
group of specific problems, using the existing 
high-voltage equipment, concurrently with 
the construction of the cyclotron. These 
efforts already have been valuable in a num- 
ber of ways, even including modification of 
the building plans to incorporate features 
peculiar to the requirements of simultaneous 
tracer-work with different radioactive ele- 
ments, recognized only as a result of operat- 
ing two such projects simultaneously. The 
gaining of experience on a small scale before 
attempting to utilize the great output from 
a 60-inch cyclotron has been valuable to the 
cooperating agencies as well. 

Shielding 

The powerful radiations from a cyclotron 
are dangerous for personnel of the laboratory 
unless arrangements for adequate shielding are 
provided. In addition, much smaller amounts 
of stray radiation or activity in the rooms of 
the laboratory will give a large and fluctuat- 
ing background on the instruments used for 
following radioactive tracer-samples. The 



shielding arrangements necessary for a speci- 
fied reduction of intensity were not known, 
but calculations made on the basis of measure- 
ments using the Department's high-voltage 
equipment, checked by rough measurements 
on existing cyclotron-installations, indicated 
the necessity for completely enclosing the 
60-inch cyclotron, and providing an 8-foot 
cover of moist earth overhead to prevent back- 
scattered radiation from the air above the 
laboratory. Numerous technical features were 
incorporated in the building to reduce the 
importance of stray radiations, including a 
separate instrument-room, shielded over all 
by an additional 3 feet of earth, for measure- 
ments at high sensitivity. The shielding for 
personnel was based on hospital experience 
with X-rays, but an added safety-factor of 
10 was used because of the still unknown 
risks of radiation-exposure. Study of the 
shielding question showed that, although 
geneticists emphasize the cumulative heredi- 
tary effect of radiation-exposure, no genetic 
experiments using other than massive single 
doses of radiation have been performed, even 
with Drosophila. Arrangements were accord- 
ingly made for a preliminary test of the 
genetic effects of continuous radiation-expo- 
sure (20 roentgens per day) over six or seven 
generations of Drosophila, the experiments 
being made jointly by the National Cancer 
Institute and Dr. Demerec of the Institution's 
Department of Genetics. Cowie stimulated 
this investigation and also arranged for the 
Cancer Institute to undertake a survey of the 
actual exposure to radiation (X-rays and 
gamma rays) of the personnel in various 
near-by hospitals and clinics. About half of 
these groups exceeded the customary toler- 
ance-dosage of 0.1 roentgen per day. This 
survey is being extended to all parts of the 
United States. 

Cooperation in Biology and Chemistry 

Photosynthesis. Cooperative experiments 
over several months were made at the Depart- 
ment with the Institution's Division of Plant 
Biology, using radioactive carbon (C 11 ) for 
studies of the various ways in which plants 



90 



CARNEGIE INSTITUTION OF WASHINGTON 



take up carbon dioxide for use in photo- 
synthesis. A plant has a reservoir-mechanism 
for carbon dioxide taken in from the sur- 
rounding air. The absorption of C0 2 into 
living sunflower leaves by solution in the 
water of the sap, by reaction with insoluble 
carbonates, and by reaction with the soluble 
buffer-substances were processes found to be 
in operation. In addition, CO a reacts to form 
a non-carbonate derivative of which little is 
yet known. It has been found that the active 
absorption of C0 2 is not a necessary part of 
the initial photochemical reaction, since C0 2 
absorbed before illumination can be used for 
the process of photosynthesis. Whether the 
carbon newly assimilated in photosynthesis 
is lost by respiration more rapidly than the 
carbon from other organic compounds already 
contained in the leaf has not been determined, 
but it was shown that this loss due to respira- 
tion is rapid. 

Arsenic. Another project in this initial 
program of cooperation in biology and chem- 
istry was the study of the distribution of 
radioactive arsenic in animal tissues in co- 
operation with Dr. Ernst A. H. Friedheim, 
of the University of Geneva. Friedheim, 
Abelson, and Cowie used radioactive arsenic 
for the synthesis of a pair of arsonic acids, 
one of high chemotherapeutical activity 
(arsanilic acid), and the other of no chemo- 
therapeutical activity (p-arsonobenzoic acid). 
The distribution of the arsenic of these 
compounds in various organs of rats, guinea 
pigs, and rabbits was studied in vitro and 
in vivo, the arsenic concentration being 
determined quantitatively by measurements 
of radioactivity. Both compounds had similar 
distribution in animal organs with the excep- 
tion of the blood. Both showed a definite 
accumulation of arsenic in the kidney, liver, 
and skin, as compared with the blood. The 
concentration in the brain, however, was only 
a fraction of that in the blood. It was also 
found that the red blood cells of the rat 
concentrated the arsenic of the chemothera- 
peutic arsanilic acid in vivo and to a lesser 
extent in vitro, whereas the arsenic of the 
inactive p-arsonobenzoic acid was not con- 
centrated in these cells. This finding will be 



highly significant if it proves to be generally 
true of chemotherapeutic compounds. The 
concentration of arsanilic acid in the blood 
was determined as a function of time and 
mode of administration. 

Placental permeability. Drs. Louis B. 
Flexner and H. A. Pohl, of the Department 
of Anatomy, Johns Hopkins University, were 
assisted in an investigation using radioactive 
sodium (Na 24 ) to measure the transfer of 
sodium across the placenta in several groups 
of animals. Each group of animals studied 
had a different placental structure. The 
experiments with the cat have shown several 
interesting results. The fetus comes to within 
10 per cent of a limiting equilibrium-value 
with respect to sodium ions in the maternal 
plasma after 16 hours, in striking contrast 
with the extracellular fluid of the mother, 
which comes to the same equilibrium in about 
4 minutes. The rate of transfer to the placenta 
(per unit-weight of placenta) has been shown 
to be very low in the earlier stages of preg- 
nancy (15 to 20 days), but increases linearly 
to 60 times this value at 57 days. A decrease 
to term is then observed in this rate. The 
rate of transfer to the fetus, however, is high 
in these earlier stages and falls off with 
duration of pregnancy. This may be ex- 
plained on the basis of the ratio of the size 
of the placenta to that of the fetus, this ratio 
decreasing as the fetus develops. 

Neutron-irradiation. Dr. Demerec, of the 
Institution's Department of Genetics, has in 
the past investigated the dosage-effect relation- 
ship of 1000 to 5000 roentgens of X-rays on 
Drosophila, both by genetic and by cyto- 
logical methods. To determine the compara- 
tive effects with neutron-irradiation, Drosoph- 
ila of the same strain used for the X-ray 
investigations were given 2000 "roentgens" 
of neutron exposure and sent to Demerec for 
analysis. One interesting point being ex- 
amined is whether the intense local ionization 
due to neutron-recoils may produce a higher 
frequency of multiple chromosomal breaks 
than with X-rays. Further work will be 
undertaken with the higher neutron-yields of 
the new cyclotron. 

Neutron-bombardments of tissue-cultures 



DEPARTMENT OF TERRESTRIAL MAGNETISM 



91 



were made for Dr. George O. Gey, of the 
Johns Hopkins University. Measurements 
made on the radiation received by his control 
tissue-cultures revealed that these controls 
accidentally received from 40 to 100 times 
the residual irradiation normally arising from 
radioactivity of surroundings, owing to the 
proximity of radium sources. One of these 
control-cultures of normal rat tissue under- 
went a spontaneous transformation and 
acquired tumor-producing characteristics, 
proved by injection and growth. This malig- 
nant transformation is of special interest in 
connection with the question of the effects 
of long-continued irradiation. 

Plant-nutrition. Radioactive sodium and 
phosphorus samples were supplied to Dr. 
Keith Brewer, of the U. S. Department of 
Agriculture, for certain studies in plant- 
nutrition. He measured the absorption and 
elimination of these elements by plant-roots 
in relation to temperature, pH, antagonistic 
ions, and other factors. 

Miscellaneous. Each of the above cooper- 
ative projects required a considerable amount 
of preliminary effort and joint endeavor of 
physicist and biologist before the actual meas- 
urements could be made on a selected prob- 
lem. Measuring instruments and techniques 
suitable for use on a variety of different 
problems and capable of yielding satisfactorily 
accurate results without difficulties of mainte- 
nance in the cooperating laboratories had to 
be devised and tested. Suitable instruments 
are not commercially available, and arrange- 
ments were made for having them con- 
structed to order. Each new group which 
joins this program will require such instru- 
ments. A special technique adapted to 
measuring the radioactivity of liquid samples, 
involving the solution of various unexpected 
difficulties before accurate measurements could 
be assured, was developed as a necessary pre- 
liminary to the work with radioactive carbon. 
This work also required a careful determina- 
tion of the decay-period of C 11 , since measure- 
ments of the activity after periods exceeding 
2 hours, or six times the half-life, were 
required as ratios to the initial activity with 
an accuracy of 1 or 2 per cent. 



With the help of Dr. U. Fano, of the 
Washington Biophysical Institute, attention 
was given to various theoretical aspects of 
biophysical problems, in particular with re- 
gard to the so-called "hit-theory" of the 
biological action of radiation, as well as other 
mathematical aspects of radiation and genetic 
problems. 

Publications 

Problems relating to the above investiga- 
tions are noted in the bibliography at the end 
of this report. 

Demonstrations of uranium fission, radio- 
active tracers, and artificial radioactivity were 
conducted in connection with the annual 
exhibition of the Institution and with various 
lectures relating to research in nuclear physics. 
Many addresses were prepared for meetings 
of scientific societies and for physics colloquia, 
including those at the California Institute of 
Technology, Catholic University of America, 
Cornell University, George Washington Uni- 
versity, Johns Hopkins University, University 
of Illinois, and University of California. 

Cooperation in Nuclear Physics at the 
University of Wisconsin 

Professor G. Breit, of the University of 
Wisconsin, continued as Research Associate 
and consultant. The results of investigations 
by him and his associates are here sum- 
marized. 

Proton-proton scattering. The p-wave ef- 
fects on Bethe's neutral form of meson theory 
have been calculated in collaboration with 
Kittel and Thaxton for proton-energies of 
2.0, 2.4, and 3.0 mev. The range of nuclear 
force corresponding to a meson mass of 180 
electron-masses gives effects of the order of 
a few per cent of the total scattering. These 
effects do not vanish at the scattering angle 
of 45 . Comparison of the theoretical and 
experimental angular distributions indicates 
at present that p-wavc effects predicted by 
the above meson theory with a mass of 180 m 
are too large, since they give too much small- 
angle scattering. 

The theoretical phase-shift curves and ex- 



9 2 



CARNEGIE INSTITUTION OF WASHINGTON 



pected scattering due to the s-wave anomaly 
have been calculated by Hoisington and 
Thaxton. The Gauss error well and the 
square well have been found to give similar 
extrapolations up to 10 mev. 

Neutron-proton scattering. Expansions for 
the computation of .f-wave scattering for 
square wells have been arranged in a form 
convenient for numerical substitution so as 
to facilitate such calculations by experimental- 
ists. Effects on p-wave scattering have been 
estimated using Bethe's neutral form of 
meson theory. Effects of the order of 50 per 
cent in the angular distribution may be 
expected for 16-mev neutrons. A possibility 
of a test of this theory is thus indicated by 
experiments on the scattering of high-energy 
neutrons. 

Metastability of hydrogen and helium levels 
of atoms in interstellar space. In collaboration 
with Professor E. Teller, of the George Wash- 
ington University, it has been found that the 
mean life of the 2^-state of hydrogen in the 
absence of collisions is primarily determined 
by the simultaneous emission of two photons. 
For this reason the mean life is about 1/7 sec. 
It is expected that the mean life of is is X S 
of He I is of the same order of magnitude 
and that it is much shorter than that of 
is is 3 S of He I. The non-adiabatic collisions 
with electrons are more important than the 
static effects at small electron densities, lead- 
ing to a transition-probability of 1/600 sec" 1 
for an electron-temperature of 1 0,000 ° C and 
an electron-density of 30 cm" 3 . The effect of 
static electric fields has been determined in 
more detail than previously. Radiations due 
to quadrupole and magnetic dipole effects 
have been considered qualitatively for is is S S 



of helium and quantitatively for is of hydro- 
gen. Experimental evidence supporting the 
theory for helium has been found by Wilson, 
of Mount Wilson Observatory. According to 
his observations it is probable that the life of 
is is X S of He I is limited by double photon- 
emission. 

Interpretation of resonances in nuclear re- 
actions. Mathematical difficulties make it 
impossible to solve the collision-problems of 
nuclear reactions accurately. The approxi- 
mate methods used, heretofore, have errors 
which are difficult to estimate. For this reason 
new methods have been introduced which 
give practically exact solutions in special cases 
designed to represent nuclear reactions sche- 
matically. Application of these methods indi- 
cates the importance of states of excitation of 
the residual nucleus in the description of re- 
actions. The way in which potential-barriers 
affect the reaction-probability has been deter- 
mined in some typical cases. 

Relativistic corrections in proton-proton 
scattering. These have been computed by L. E. 
Hoisington. Small but eventually detectable 
effects on the range of force have been found. 

Shot-effect calculations. Calculations of 
shot-effect with a square-law detector have 
been made. 

Fine structure of nuclear levels. The fine 
structure of He 5 has been estimated in con- 
nection with observations by Stephens and 
Staub on neutron-scattering in He. A larger 
theoretical structure has been found on the 
one-body picture of scattering than by Dan- 
coff. His arguments against the explanation 
in terms of spin-orbit forces do not appear to 
be conclusive. 



FIELD-WORK AND REDUCTIONS 

LAND MAGNETIC SURVEY 



The results of magnetic observations on 
land during 1927-1939 were revised by 
Wallis and Vestine, and preparation of manu- 
script for publication was begun. Summaries 
of magnetic data for Africa, Australia, and 
South America, including determinations of 



latitude and longitude, were furnished a 
number of interested government and pri- 
vate organizations. 

The Department has cooperated through 
the loan of field-instruments to the Cape 
Town, Cheltenham, Government of South 



DEPARTMENT OF TERRESTRIAL MAGNETISM 



93 



Australia, and Apia observatories, and to the 
British East African Meteorological Service, 
the Aerial, Geological, and Geophysical Sur- 
vey of Northern Australia, and the U. S. 
Antarctic Service. Constants and corrections 
on field-instruments were maintained in co- 
operation with the U. S. Coast and Geodetic 
Survey. 

Increased attention has been directed to the 
use of local detailed magnetic surveys in 
obtaining geological information not readily 
forthcoming in other ways. A total of 745 
stations were occupied with vertical-force 
variometers by Green in the environs of the 
volcano Santa Maria in Guatemala, on an 
expedition headed by Zies, of the Geophysical 
Laboratory. Most of these stations were inter- 
mediary in spacing between those obtained 
by McNish in 1939 and serve to assist in 
averaging out the apparently marked influ- 
ences of surface rocks from the larger main 
systematic magnetic changes associated with 
the volcano. The distribution and number 
of stations are probably as yet inadequate for 
careful inferences respecting the internal 
structural features of the volcano, in conjunc- 
tion with other geophysical data, but the re- 
sults will be used in a preliminary study. 
Green also reoccupied two permanent repeat- 
stations in Guatemala. 

Johnson effected improvements in the de- 
sign of a new electromagnetic field-magnet- 
ometer. Its construction is being postponed 
pending completion of the Fleming coil- 
magnetometer. 

Grave concern is being occasioned by the 
present lack of magnetic observations over 
the oceans, which comprise the major part 
of the Earth's surface-area. Investigations 
are under way to determine the utility of 
continental observations in computing a rough 
continuation across the oceans of the field as 
observed on land, as well as the number, 



accuracy, and type of observations required 
on land. This project can yield at best but 
makeshift results, even though theoretically 
an accurate knowledge of the field-distribu- 
tion over a single continent would suffice to 
determine the field at all points elsewhere on 
the Earth's surface. In problems of this kind 
a large number of observations of moderate 
accuracy would be more useful than a small 
number of observations of great accuracy, 
because the rate of change of the field with 
distance along the Earth's surface should be 
well defined. The problem of adjusting 
observations in conformity with the require- 
ments of potential-theory is also under con- 
sideration in connection with improvements 
in techniques of constructing magnetic charts. 

Field-Operations and Cooperative Surveys 

Secular-variation data in Africa were obtained 
through control-observations at the Cape Town 
Magnetic Observatory and through observations 
in Kenya Colony by the British East African 
Meteorological Service. 

In Australia control-observations supplied secu- 
lar-variation information at the Watheroo Mag- 
netic Observatory and some work was done in 
Northern Australia in cooperation with the 
Aerial, Geological, and Geophysical Survey of 
Northern Australia. 

In North America international magnetic 
standards of the Department were continued in 
cooperation with the U. S. Coast and Geodetic 
Survey at the Cheltenham Magnetic Observatory, 
where CIW sine-galvanometer 1 and CIW 
Schulze earth-inductor 48 are the standards for 
horizontal intensity and inclination. 

In connection with the Guatemalan Volcano- 
logical Expedition of 1939 for the investigation 
of the volcano Santa Maria, two secular-variation 
stations were reoccupied, namely, Guatemala City 
and Quezaltenango; besides these, in a total of 
743 stations occupied for the study of magnetic 
anomalies in 404 km along n traverses, 7 were 
repeat-stations with results for only one or two 
of the magnetic elements. 



OBSERVATORY-WORK 



Johnston continued in charge of the Section 
of Observatory-Work. The magnetic reduc- 
tions and compilations were maintained with 
the assistance of Scott and Miss Balsam. 



McNish continued the study of magnetic data 
from our observatories. Wait and Torreson 
completed the compilation of meteorological 
observations for both observatories over the 



94 



CARNEGIE INSTITUTION OF WASHINGTON 



n-year period from 1924 to 1934. The mem- 
bers of staff in residence at the observatories 
are mentioned in their respective reports. 

At Watheroo and Huancayo observatories 
continuous records were obtained of the three 
magnetic elements, of atmospheric potential- 
gradient, of positive and negative conduc- 
tivity of the atmosphere, of earth-currents, of 
heights of the ionosphere using both multi- 
and fixed-frequency, and of the meteorologi- 
cal elements, as well as daily spectrohelio- 
scopic observations during the periods as- 
signed by the International Astronomical 
Union. At the Huancayo Observatory there 
were also obtained continuous records with a 
three-component seismograph and a precision 
cosmic-ray meter. 

Half-daily character-figures were trans- 
mitted weekly from both observatories, thus 
continuing the dissemination through Science 
Service of weekly reports of the American 
magnetic character-figure, Cj_. 

Beginning April 1, 1940, both observatories 
began reporting magnetic activity on the 
more detailed basis of the 3-hour-range index 
K (see pp. 63-64), to give further assistance 
in researches in terrestrial magnetism and 
radio. The AT-indices range from for very 
quiet to 9 for extremely disturbed conditions 
and are sent by radio or cable to Washington 
weekly. Similar reports are prepared by the 
observatories of the U. S. Coast and Geodetic 
Survey at Cheltenham, Honolulu, San Juan, 
Sitka, and Tucson. At the Department in 
Washington the indices from each observa- 
tory are normalized to represent world-wide 
conditions and a mean index Ka is derived 
for each 3-hour period. Individual and mean 
indices are published weekly by Science 
Service. 

The magnetic and atmospheric-electric pro- 
grams of the Department were assisted by 
various magnetic observatories. Our inter- 
national magnetic standards were maintained 
at the Cheltenham Magnetic Observatory, 
and the program in atmospheric electricity 
and earth-currents was continued at Tucson 
Magnetic Observatory; both of these observa- 
tories are operated by the U. S. Coast and 
Geodetic Survey. At the Apia Observatory in 



Western Samoa, under the auspices of the 
Department of Scientific and Industrial Re- 
search of New Zealand, the work in atmos- 
pheric electricity was maintained with the 
cooperation of the Department of Terrestrial 
Magnetism. 

Operations at Observatories 

The operations at the observatories of the 
Department and at observatories or organiza- 
tions with which the Department cooperated 
are summarized below. 

Watheroo Magnetic Observatory, Watheroo, 
Western Australia. The Watheroo Magnetic Ob- 
servatory is situated in latitude 30 19a south 
and longitude 115 52^6 east of Greenwich, 244 
meters (800 feet) above sea-level. 

The Eschenhagen magnetograph was in con- 
tinuous operation, with but a small percentage 
of lost trace caused by occasional failure of the 
driving clock. Monthly scale-value determina- 
tions of the horizontal-intensity variometer were 
made as in previous years, using the magnetic 
deflection-method; in the case of the vertical- 
intensity balance, scale-value determinations, 
using the electrical method, were made daily. 
The monthly mean scale-values for both the 
horizontal and vertical components are given in 
table 1. 

Table i 

Scale-Values of Magnetographs, Watheroo 
Magnetic Observatory, 1939 





Scale-values in 7/MM 


Month 


Eschenhagen 


LA COUR 




H (re- 
duced to 
base-line) 


Z (means 
of daily 
values) 


H 


z 


January 

February .... 

March 

April 

May 

June 

July 


2.36 
2.36 
2.37 
2.38 
2.37 
2.36 
2.41 
2.34 
2.34 
2.38 
2.36 
2.37 


3.27 
3.29 
3.30 
3.32 
3.35 
3.35 
3.41 
3.44 
3.44 
3.45 
3.46 
3.46 


4.55 
4.54 
4.48 
4.59 
4.44 
4.50 
4.51 
4.47 
4.59 
4.55 
4.55 
4.57 


2.77 
2.58 
2.37 
2.64 
2.85 
3.04 
3.44 


August 

September. . . 

October 

November. . . 
December. . . . 


3.44 
3.06 
3.12 
3.08 
3.08 



DEPARTMENT OF TERRESTRIAL MAGNETISM 



95 



The la Cour rapid-run magnetograph was also 
in continuous operation. Scale-value determina- 
tions by the electrical method were made 
monthly as in previous years. The resulting 
values are included in table i. 

The preliminary mean values of the magnetic 
elements for all days of 1939, as deduced from 
the Eschenhagen magnetograms, referring the 
elements to the north-seeking end of the needle 
and reckoning east declination and north inclina- 
tion as positive, are: declination, —3° 2i!o; 
horizontal intensity, 0.24687 CGS unit; vertical 
intensity, — 0.51517 CGS unit; and inclination, 
— 64 23-'7. These results indicate annual 
changes as follows: declination, +5.3; horizontal 
intensity, +5 gammas; vertical intensity, —28 
gammas; and inclination — o.'4. 

The method of assigning magnetic character 
was revised in January 1940, after which time 
the reports were based on 3-hourly evaluations 
of "^-indices," these giving a measure of the pro- 
portional deviation from normal quiet conditions. 
Intercomparisons between the Observatory stand- 
ard magnetic instruments and CIW magnet- 
ometer-inductor 18, at present on loan to the 
Commonwealth Geophysical Survey, were made 
during February 1940. 

Earth-potentials, over a system of electrodes as 
described in previous reports, were recorded 
throughout the year, and the equipment has 
yielded consistent results. Periodic tests of line- 
insulation and electrode-resistance were made as 
before. 

The atmospheric-electric program, involving 
the continuous recording of air-potentials and 
positive and negative air-conductivities, was fully 
maintained, although weather-conditions during 
the calendar year 1939 were unusually adverse 
to this branch of the Observatory's activities. The 
total rainfall for the year was the highest since 
records have been obtained, that is, for 22 years; 
the monthly totals and the number of days on 
which rain fell, together with the monthly aver- 
age falls for 22 years, are shown in table 2. 

In consequence, the number of complete days 
usable in the atmospheric-electric records was 
considerably less than in 1938. As usual, on a 
certain number of days during the summer the 
records were vitiated by the presence of smoke 
from bush-fires. Reduction-factor observations, 
for correcting the values of potential-gradient as 
recorded by the standard instrument to volts per 
meter over a plane surface, were made on three 
occasions, the number being restricted because of 
the difficulty of obtaining suitable meteorological 



conditions; usually these determinations are made 
quarterly. The preliminary values of the atmos- 
pheric-electric elements are shown in table 3. 

The automatic multifrequency ionospheric re- 
cording apparatus functioned practically continu- 
ously throughout the year, the only breaks being 
during brief intervals for maintenance, overhaul, 
and minor repairs. The regular manual control 
and maintenance were performed and the scaling 
and reduction of the records were maintained 
practically current. Certain changes in scaling, 
with a view to obtaining additional information 

Table 2 

Rainfall in Inches at the Watheroo Mag- 
netic Observatory during 1939 



Month 


Monthly 
total 


No. days 


Av. monthly 

total, 

22 years 


January 

February 

March 

April 

May 

June 

July 

August 

September. . . . 

October 

November. . . . 
December. . . . 


0.81 
4.32 
0.02 
0.42 
2.95 
5.12 
5.05 
3.14 
0.21 
1.91 
0.40 
0.02 


2 
4 
1 
3 

12 

15 

18 

16 

4 

9 

7 

2 


0.35 
0.56 
1.09 
0.92 
2.18 
3.44 
3.01 
2.30 
1.26 
0.83 
0.32 
0.36 


Total 


24.37 


93 


16.61 



from the records, were made during the year in 
accordance with instructions. Quarterly reports 
on ionospheric conditions, accompanied by sum- 
maries of data and graphs, were transmitted to 
Washington for publication in the Journal of 
Terrestrial Magnetism and Atmospheric Elec- 
tricity. Preliminary mean hourly values of iono- 
spheric data for 1939 are shown in table 4. 

During the first two months of the report-year 
communication schedules were maintained with 
amateur radio stations in Philadelphia and Wash- 
ington; on the outbreak of the European war, 
however, instructions were received from the 
Postmaster-General's Department at Melbourne 
that all transmitting equipment must be dis- 
mantled and rendered inoperative. After further 
inquiry, the continuation of transmission of the 
ionosphere-recorder pulse was allowed; but the 
radio transmission of scientific data from the 



9 6 



CARNEGIE INSTITUTION OF WASHINGTON 



Table 3 

Preliminary Monthly Mean Values of Atmospheric-Electric Elements, 
Watheroo Magnetic Observatory, 1939 



Month 



No. 

SELECTED 
DAYS 



Potential-gradient 



Reduction- 
factor 



Value 
(v/m) 



Air-conductivity, unit lO -11 esu 



X+ 



(X++X-) 



(X+/X-) 



January 

February 

March 

April 

May 

June 

July 

August 

September 

October 

November 

December 

Totals and means. 



11 
7 
5 

11 
10 
14 
15 
14 
16 
12 
11 
11 



101.1 
88.5 
83.6 
91.9 
74.4 
79.4 
85.6 
92.2 
99.2 
92.2 
84.1 
92.5 



1.42 
1.73 
1.76 
1.97 
2.34 
2.49 
2.33 
2.16 
1.84 
1.83 
1.72 
1.58 



1.30 
1.68 
1.71 
1.68 
2.05 
2.21 
2.02 
1.84 
1.57 
1.58 
1.65 
1.46 



137 



1.17 



1.93 



1.73 



2.76 
3.41 
3.47 
3.65 
4.39 
4.70 
4.35 
4.00 
3.41 
3.41 
3.37 
3.04 



3.66 



1.09 
1.03 
1.03 
1.17 

1.14 
1.13 
1.15 
1.17 
1.17 
1.16 
1.04 
1.08 



1.11 



Table 4 

Preliminary Mean Hourly Values of Ionospheric Data, 
Watheroo Magnetic Observatory, 1939 



120° 
east meridian 


h F 1 


h r? 

F 2 






J F 


■T-min 


time 














(h) 


(km) 


(km) 


(mc/sec) 


(mc/sec) 


(mc/sec) 


(mc/sec) 


00 




272 






5.35 




01 




269 






5.12 




02 




266 






4.83 




03 




264 






4.60 




04 




267 






4.35 




05 




274 






4.18 




06 




266 


1.53 




4.68 




07 


238 


262 


2.35 


4.43 


6.45 


0.69 


08 


232 


277 


2.94 


4.61 


7.92 


0.83 


09 


228 


288 


3.30 


4.75 


8.83 


0.94 


10 


221 


299 


3.51 


4.98 


9.48 


0.99 


11 


218 


307 


3.63 


5.12 


9.88 


1.02 


12 


220 


308 


3.69 


5.16 


10.05 


1.04 


13 


222 


306 


3.68 


5.14 


10.15 


1.04 


14 


225 


302 


3.59 


5.04 


10.14 


1.01 


15 


229 


290 


3.41 


4.80 


10.05 


0.97 


16 


231 

235 


275 
259 
241 


3.07 
2.52 
1.74 


4.52 
4.46 


9.71 
9.28 
8.59 


0.87 


17 


0.75 


18 


0.63 


19 




238 

245 






7.51 
6.67 




20 




21 




256 






6.08 




22 




267 






5.72 




23 




269 






5.51 





DEPARTMENT OF TERRESTRIAL MAGNETISM 



97 



Observatory to Washington was discontinued. 
Subsequently arrangements were made through 
the State Department of the United States and 
the Australian Minister for Defense whereby 
weekly cabled messages of magnetic character 
would be allowed to be dispatched by the United 
States Consul in Perth on our behalf, and since 
then this plan has been satisfactorily continued. 

Visual observations of solar activity with the 
Hale spectrohelioscope were continued on all 
possible days during the three half-hour periods 
assigned by the International Solar Committee, 
and monthly reports have been prepared and 
transmitted to Washington. 

The usual meteorological observations as out- 
lined in previous reports were made daily, and 
all the self-recording meteorological instruments 
were kept in continuous operation. Besides being 
used in the control of the Observatory's recording 
instruments, the information is supplied monthly 
to the Australian Commonwealth Weather 
Bureau at Melbourne as in previous years. In- 
cluded in the meteorological observations are 
daily quantitative determinations of condensation- 
nuclei, using the Aitken nuclei-counter. 

Scientific data and information as to equip- 
ment and technique were supplied, on request, 
to collaborators in Australia and elsewhere. Co- 
operation in ionospheric research continues be- 
tween the Observatory and the Commonwealth 
Radio Research Board. Parkinson attended the 
Conference of Physicists and Astronomers held 
in Melbourne during August 1939, and also meet- 
ings, in Perth, of the West Australian Section 
of the Institute of Physics. 

The tabulation and reduction of observatory- 
data are practically current, although toward the 
end of the report-year, owing to changes of staff 
and other causes, some slight arrears were 
accumulated. 

The need for further office space, especially felt 
after the inauguration of the ionospheric research 
program, and the desirability of a more orderly 
and accessible arrangement of the growing li- 
brary of the Observatory led to the erection of 
a new office, removed from the variation-observa- 
tory and therefore unhampered by restrictions 
as to the nonmagnetic character of its contents. 
This building was completed and occupied in 
October 1939. The old office was converted into 
a library, in which adequate space for the storage 
of books and periodicals will be provided for 
many years to come. 

The building which formerly housed the 
atmospherics recorder (on loan from the Com- 



monwealth Radio Research Board), given to the 
Observatory on the completion of the research 
in atmospherics, was removed to another site and 
was outfitted as a darkroom for all the photo- 
graphic work of the Observatory. It also houses 
the anemograph which was formerly mounted 
in the auxiliary quarters. 

In order to provide a necessary margin of 
electrical power, and also from considerations of 
economy, a Stover Diesel engine-generator of 
15 horsepower was installed at the end of 1939; 
the necessary fuel storage-tank and filter-system 
were also erected. The Kohler engine-generators 
continue in service during times when the Diesel 
is under overhaul or being serviced. 

Replacement of the overhead power and 
general wiring system of the Observatory by an 
underground, lead-covered cable-system was 
about 50 per cent completed. The buildings, 
grounds, and auxiliary equipment were kept in 
order. 

The Observatory has been fortunate in the con- 
tinued enjoyment of the good will and coopera- 
tion of government departments and private indi- 
viduals, without whose ready aid the prosecution 
of the program would be almost impossible, espe- 
cially under present world conditions. Specific 
mention should be made of the officials of the 
Commonwealth Postmaster-General's Depart- 
ment, especially the Senior Radio Inspector in 
Perth, Mr. G. ,A. Scott, for their interest in our 
work and for special permission to continue the 
ionospheric transmissions in spite of the rigorous 
curtailment of general radio activity in Australia 
necessitated by the war. The Commonwealth 
Department of Trade and Customs has continued 
its beneficent attitude by allowing the importa- 
tion of necessary equipment and supplies free of 
duty. The United States consular staff in Perth 
have been most helpful in the matter of cabling 
our weekly magnetic-character messages. Senator 
H. B. Collett, C.M.G., has rendered valuable 
assistance by making representations in the Ob- 
servatory's interests to government departments 
in Canberra; Professor A. D. Ross, of the Uni- 
versity of Western Australia, has continued his 
interest in the Observatory and has given assist- 
ance in various ways. 

Parkinson continued as Observer-in-Charge, 
with Prior as first assistant. Chamberlain, junior 
observer until March 31, 1940, resigned to take an 
appointment at the Mount Stromlo Solar Observ- 
atory and was succeeded by C. H. Muhling on 
April 13, 1940. McCarthy continued as junior 
observer throughout the report-year. George 



98 



CARNEGIE INSTITUTION OF WASHINGTON 



continued as mechanic, with McCall as assistant 
mechanic. The successful prosecution of the 
comprehensive and increasing program is evi- 
dence of the continued energy and efficiency of 
all members of the staff. 

Huancayo Magnetic Observatory. The Ob- 
servatory is situated in latitude 12° 02.J south 
and longitude 75 2o'4 west of Greenwich, in 
the central valley of the Peruvian Cordillera at 
an elevation of 3350 meters (11,000 feet) above 
sea-level. 

F. T. Da vies was Observer-in-Charge through 
September 1939, at which time he resigned for 
active service with the British forces. H. W. 
Wells has been Observer-in-Charge since October 
1939, with W. Culmsee and R. C. Coile as assist- 
ants, the latter joining the scientific staff at the 
Observatory in October 1939. Among the Peru- 
vian employees, T. Astete, A. Macha, and V. 
Murga continued as clerical assistants throughout 
the year. 

Eight major instruments and several meteoro- 
logical recorders, as listed below, were operated 
during the year. 

Two magnetographs, one an Eschenhagen, the 
other a la Cour rapid-run type, were operated 
continuously. Control of base-lines was obtained 
by weekly absolute magnetic observations. Scale- 
values for declination and horizontal intensity of 
the Eschenhagen magnetograph were determined 
electrically once each week, and the scale-value 
for vertical intensity was determined electrically 
three times each week. Scale-values for hori- 
zontal intensity and vertical intensity of the la 
Cour magnetograph were determined electrically 
once each month. An additional la Cour hori- 
zontal-intensity variometer was operated at low 
sensitivity with the Eschenhagen magnetograph. 
Monthly reports of the more important magnetic 
disturbances were forwarded to the Washington 
office. 

Air-potentials were recorded with standard 
potential-gradient apparatus and scale-values 
were determined twice each month. Reduction- 
factors were obtained by comparison with poten- 
tials measured over open, level ground at 
quarterly intervals. 

Air-conductivities (positive and negative) were 
continuously recorded and scale-values were 
determined every two weeks. The installation 
of a synchronous motor-drive operated from the 
60-cycle, alternating-current supply in place of 
the variable-speed, direct-current motor in the 
calibration-equipment resulted in greater accu- 
racy and simplicity of calibrations. 



Earth-current potentials were recorded con- 
tinuously with the Leeds and Northrup appa- 
ratus. The use of two separate systems of north- 
south and east-west electrodes was continued. 

The horizontal-component Wenner-type and 
vertical-component Benioff-type seismographs 
were operated. The Wenner seismograph was 
operated continuously, recording earth-move- 
ments in the north-south and east-west planes. 
Following overhaul and slight modification by 
the manufacturer, the Benioff apparatus was 
reinstalled in January 1940. Operation of this 
instrument is now very satisfactory. Analyses of 
the more important seismic disturbances were 
made regularly and code-messages were trans- 
mitted to the Washington office by amateur radio. 
The Peruvian earthquake of May 24, 1940, which 
caused appreciable damage along the coast, was 
also felt at the Observatory although no damage 
was done. The north-south instrument gave a 
complete recording of earth-tremors for this date. 
The east-west instrument, however, was thrown 
off scale with the initial movement, and did 
not return to normal recording position. 

A Compton-Bennett cosmic-ray meter recorded 
cosmic-ray intensities continuously. Reduced 
cosmic-ray intensities during periods of strong 
magnetic disturbances are evident from casual 
examination of the records. 

The Hale spectrohelioscope was used daily, as 
conditions of clouds permitted, for observation 
of the Sun. The assigned daily periods of obser- 
vation for Huancayo are from 15 11 30 111 to i6 h and 
from i6 h 30™ to iy h GMT, according to the inter- 
national program. Monthly reports of results of 
spectrohelioscope observations were prepared. 
These formed the basis for quarterly reports for- 
warded to the International Astronomical Union 
from the Washington office. 

The multifrequency ionospheric recorder was 
operated continuously except for short intervals 
necessary for maintenance and minor modifica- 
tions or repairs. Scalings and tabulations of 
critical frequencies and virtual heights of the 
several ionospheric regions were kept current. 
Quarterly reports giving summaries of average 
ionospheric conditions and trends were for- 
warded for publication in the Journal of Terres- 
trial Magnetism and Atmospheric Electricity. An 
annual report was prepared, summarizing the 
results of the second full year of continuous 
recording. It was shown that the generally pre- 
dominant features and characteristics for 1939 
were similar to those reported for 1938. These 
include the annual trend of F 2 - re gi° n penetra- 



DEPARTMENT OF TERRESTRIAL MAGNETISM 

Table 5 

Preliminary Monthly Mean Values of Atmospheric-Electric Elements, 
Huancayo Magnetic Observatory, 1939 



No. 

SELECTED 
DAYS 



Potential-gradient 



Reduction- 
factor 



Value 

(v/m) 



Air-conductivity, unit 10 -4 esu 



X+ 



X- 



(X++X-) 



(X+A-) 



January 

February 

March 

April 

May 

June 

July 

August 

September 

October 

November 

December 

Totals and means. 



4 

2 
4 
6 
10 
10 
6 

10 
5 
5 
3 
3 



1.19 



42.8 
48.2 
53.9 
43.8 
52.5 
56.6 
49.3 
56.4 
52.6 
46.1 
49.5 
51.9 



4.58 
3.82 
3.92 
5.02 
4.10 
4.27 
4.77 
4.83 
3.93 
4.69 
4.95 
4.59 



4.56 
3.91 
3.80 
5.14 
4.19 
4.30 
5.00 
5.36 
3.88 
5.01 
5.26 
4.58 



50.3 



4.46 



4.58 



9.14 

7.73 
7.72 

10.16 
8.29 
8.57 
9.77 

10.19 
7.81 
9.70 

10.21 
9.17 



9.04 



1.00 
0.98 
1.03 
0.98 
0.98 
0.99 
0.95 
0.90 
1.01 
0.94 
0.94 
1.00 



0.98 



Table 6 

Preliminary Mean Hourly Values of Ionospheric Data, 
Huancayo Magnetic Observatory, 1939 



75° 

west 

meridian 

time 

(h) 



'1 
(km) 



r 2 
(km) 



(mc/sec) 



(mc/sec) 



(mc/sec) 



J min 
(mc/sec) 



00 
01 
02 
03 
04 
05 
06 
07 
08 
09 
10 
11 
12 
13 
14 
15 
16 
17 
18 
19 
20 
21 
22 
23 



241 
232 
222 
215 
211 
209 
207 
209 
214 
231 



251 
249 
252 
254 
258 
259 
270 
259 
278 
289 
304 
314 
319 
318 
310 
297 
286 
260 
296 
345 
333 
298 
273 
259 



0.76 
1.76 
2.66 
3.27 
3.65 
3.85 
4.00 
4.04 
3.95 
3.79 
3.54 
3.08 
2.49 
1.46 
0.78 



4.58 
4.99 
5.21 
5.36 
5.43 
5.46 
5.38 
5.23 
4.95 
4.59 



8.36 

7.73 

6.91 

6.09 

5.38 

4.88 

6.50 

9.30 

10.86 

11.51 

11.39 

11.01 

10.86 

10.86 

10.92 

10.97 

10.97 

10.86 

10.54 

9.79 

9.27 

9.14 

8.92 

8.75 



0.65 
0.87 
1.08 
1.39 
1.69 
2.00 
2.14 
2.19 
2.14 
2.02 
1.70 
1.26 
0.96 
0.94 
0.70 



100 



CARNEGIE INSTITUTION OF WASHINGTON 



tion-frequencies, and the unusual fact that the 
F 2 -region virtual heights seem to assume the 
features of typical variations of both northern 
and southern hemispheres, with no pronounced 
local seasonal effects. 

A fixed-frequency ionospheric recorder oper- 
ating on 4800 kc/sec was constructed and in- 
stalled at the Observatory in August 1939. Since 
then, the equipment has been rebuilt into panels 
of permanent construction. The results have 
been most useful for analyses and interpretations 
of radio fade-outs; the latter are frequently 
associated with a sharp increase in horizontal 
intensity, similar in appearance to a sudden 
commencement. 

Special ionospheric recordings of radio-wave 
polarization were conducted in January 1940, 
using a rotatable antenna-system. The results, 
which have been reported in a separate paper, 
confirm and extend the conclusions made from 
other tests conducted here by Wells in 1935. 

Radio communication with John B. Morgan's 
amateur radio station, W3QP (Blue Bell, Penn- 
sylvania), was maintained by the Observatory's 
station, OA4U, to forward magnetic data, reports 
of earthquakes, and other information of a scien- 
tific nature. Following the order of the Federal 
Communications Commission prohibiting United 
States communications with foreign countries by 
amateurs, this material has been broadcast from 
OA4U with satisfactory results. 

The 6-kw Diesel engine-generator for power- 
supply continues quite satisfactory. It is operated 
continuously except for short periods of mainte- 
nance or overhaul. Associated equipment, includ- 
ing the direct-current voltage-control system used 
to automatically adjust the output of the Diesel 
to the varying load-requirements, continues to 
be satisfactory. 

Observations of barometric pressure, maximum 
and minimum temperatures, relative humidity, 
rainfall, cloudiness, and direction and velocity 
of wind were made daily at o8 h , 75 west 
meridian time. Measurements of the air-content 
of condensation-nuclei were made daily at the 
same hour. Continuous records were obtained 
with barograph, thermograph, hygrograph, ane- 
mometer, and sunshine-recorder. 

Computations and tabulations of magnetic, 
atmospheric-electric, earth-current, ionospheric, 
and meteorological studies were kept current. 
Records and tabulations were forwarded each 
month to the Washington office, together with 
seismograms, cosmic-ray records, and solar data 
obtained with the spectrohelioscope. The Ob- 



servatory continued to supply copies of monthly 
tabulations of meteorological results (including 
barometric pressure, direction and velocity of 
wind, and sunshine) to the Servicio Meteoro- 
logico Nacional del Peru and also to the Centro 
Geografico Departamental de Junin, Peru. 

In accordance with the resolution passed by the 
Association of Terrestrial Magnetism and Elec- 
tricity at Washington in September 1939, adopt- 
ing 3-hour-range indices (K) to characterize the 
variation in the degree of irregular magnetic 
activity throughout each day, this Observatory 
has been providing tabulations of K-indices since 
January 1940. 

Preliminary mean values of the magnetic ele 
ments for all days of 1939 as deduced from the 
Eschenhagen magnetograms, referring the ele- 
ments to the north-seeking end of the needle and 
reckoning east declination and north inclination 
as positive, are: declination, +7 004; hori- 
zontal intensity, 0.29553 CGS un it; vertical in- 
tensity, 0.01162 CGS unit; inclination, + 2 15'n:. 
The preliminary values for the annual changes 
in the magnetic elements during 1938.5 to 1939.5 
are: declination, — 4^2; horizontal intensity, 
— 19 gammas; vertical intensity, —5 gammas; 
inclination, — o'5. 

Preliminary monthly mean values of the at- 
mospheric-electric elements are given in table 5. 
Reduction-factor observations were made 
quarterly. 

Mean hourly values of ionospheric data for 
the several ionospheric regions are given in 
table 6, where h refers to virtual height and 
/ indicates penetration-frequency, while the sub- 
scripts show the particular ionospheric region. 
All data refer to the ordinary wave-component 
only. 

The successful continuance of the program has 
been possible because of the hearty cooperation 
of the scientific staff, with the definite assistance 
of the Peruvian employees. 

Cooperation with Other Observatories 

Cheltenham Magnetic Observatory, United 
States. The cooperative program with this Ob- 
servatory under the direction of the U. S. Coast 
and Geodetic Survey was continued. CIW sine- 
galvanometer 1 and CIW earth-inductor 48 were 
used for absolute standards in horizontal in- 
tensity and inclination. With the generous as- 
sistance of Observer-in-Charge Ludy and G. Hart- 
nell of the Observatory's staff, the precision 
cosmic-ray meter furnished automatic records of 



DEPARTMENT OF TERRESTRIAL MAGNETISM 



101 



cosmic-ray intensity, and the CIW perminvar 
vertical-intensity induction-variometer gave de- 
pendable records of magnetic vertical intensity 
to April n, 1940, when it was returned to the 
Department and set up in the Standardizing 
Magnetic Observatory. The necessary controls of 
the magnetic equipment used in Guatemala and 
on the U. S. Antarctic Expedition were obtained 
with the cooperation of the Cheltenham Observa- 
tory staff. 

Apia Observatory, Western Samoa. The De- 
partment continued cooperation with this Ob- 



1939 there occurred 117 days of zero-character 
with a mean value of 116.9 volts per meter. 
These results and a summary of the meteorologi- 
cal elements are given in table 7. The annual 
average hourly values in volts per meter based 
on the monthly means are as follows: 90, 86, 89, 

9°, 95, I0 3, r 45, 2I 7> 2I 9> I53> I2I > I0 5> I00 > 94. 
93, 90, 88, 93, 119, 166, 146, 121, 101, 89. 

Tucson Magnetic Observatory, United States. 
The Department's equipment for recording 
atmospheric potential-gradient, positive and 
negative air-conductivities, and earth-currents, 



Table 7 
Potential-Gradient and Meteorological Summary, Apia Observatory, 1939 



Potential-gradient 



No. 
zero-days 



Value 
(v/m) 



Meteorological elements 



Pressure 
(inches) 



Temp. 
(°F) 



Rainfall 

(inches) 



Rel. hum. 
9 A.M. 

(per cent) 



Sunshine 
(hours) 



Wind 

velocity 

(miles/hr.) 



January 

February 

March 

April 

May 

June 

July 

August 

September 

October 

November 

December 

Totals and means . 



2 

4 

5 

12 

10 

1Q 

18 
16 
5 
15 
12 



,110 
109 
112 
127 
118 
110 
139 
128 
112 
120 
112 
108 



29.788 
29.776 
29.792 
29.833 
29.842 
29.874 
29.878 
29.829 
29.882 
29.839 
29.784 
29.791 



78.3 
79.4 
78.6 
79.1 
78.9 
77.9 
78.1 
79.0 
78.1 
79.3 
80.1 
79.3 



59.57 

18.65 

17.95 

9.00 

2.35 

1.57 

3.28 

2.13 

7.87 

11.17 

5.98 

11.66 



83 
81 
84 
81 
78 
74 
75 
74 
80 
71 
75 
75 



175.3 
149.9 
186.4 
208.0 
274.7 
272.0 
302.1 
291.5 
203.2 
250.4 
256.1 
202.7 



7.8 
9.2 
4.7 
6.4 
5.6 
5.8 
5.5 
7.9 
5.7 
7.5 
4.8 
4.7 



117 



117 



29.826 



78.8 



151.18 



78 



2772.3 



6.3 



servatory through its Acting Director, H. B. 
Sapsford, and staff in the program in terrestrial 
magnetism and atmospheric electricity. This 
Observatory also undertakes observations in other 
fields of geophysics, including meteorology and 
seismology. 

CIW magnetometer 9 and CIW earth-inductor 
2 were on loan for absolute observations of 
declination, horizontal intensity, and inclination. 
Continuous photographic records were obtained 
of declination, horizontal intensity, and vertical 
intensity during the report-year. Declination and 
horizontal intensity were recorded with Eschen- 
hagen variometers and vertical intensity with a 
Godhavn balance. 

Atmospheric potential-gradient was measured 
with a Benndorf electrometer. Standardization- 
observations for reduction-factor confirmed that 
the previous factor of 1.00 still applied. During 



through the cooperation of the U. S. Coast and 
Geodetic Survey, was efficiently operated and 
controlled by Observer-in-Charge J. Hershberger 
and R. F. White. The preliminary scaling of the 
atmospheric-electric observations was done by 
Mrs. G. Dewey in part-time service of the Depart- 
ment. The preliminary monthly and annual 
values of the atmospheric-electric elements are 
given in table 8. 

The line-connections to the electrodes were 
maintained through the courtesy of the Bell 
Telephone Laboratories. The earth-current rec- 
ords are normally complete for the year. Earth- 
current records for this and previous years were 
extensively used in an investigation of earth- 
current activity with the sunspot-cycle. 

Cape Town Magnetic Observatory, South 
Africa. Cooperation with this Observatory of 



102 



CARNEGIE INSTITUTION OF WASHINGTON 



the Magnetic Branch of the Trigonometrical 
Survey of the Union of South Africa was con- 
tinued through the loan of apparatus. Control 
of declination, horizontal intensity, and vertical 
intensity is maintained using CIW magnetometer 
17 with earth-inductor attachment. 

Royal Alfred Observatory, Mauritius, Indian 
Ocean. The loan of CIW marine-inductor 4 and 
galvanometer to this Observatory was continued 
for the control of the vertical-intensity records. 

College, Alaska. Professor E. H. Bramhall con- 
tinued work in the laboratory preparing equip- 
ment for recording ionospheric conditions. 



kept current at the Tucson Magnetic Ob- 
servatory. Scale-values are being examined 
and analyzed as a function of temperature 
and time and appropriately assigned by Sher- 
man preliminary to the computing of the 
final values of the three elements, potential- 
gradient, positive conductivity, and negative 
conductivity. At present it seems that: (a) 
the potential-gradient reduction-factor may 
with sufficient precision be regarded as a 
constant, namely, 1.24 during 1931 to 1939; 
(b) in general, the scale-value for both posi- 



Table 8 

Preliminary Monthly Mean Values of Atmospheric-Electric Elements, 
Tucson Magnetic Observatory, 1939 



No. 

SELECTED 
DAYS 



Potential-gradient 



Reduction- 
factor 



Value 
(v/m) 



Air-conductivity, unit 10 -4 esu 



X+ 



(X++X-) 



(X+/X-) 



January 

February 

March 

April 

May 

June 

July 

August 

September 

October 

November 

December 

Totals and means. 



15 
19 

27 
15 
28 
24 
4 
9 
18 
19 
15 
22 



1.27 
1.24 
1.22 



1.22 
1.29 



57.7 
62.1 
47.6 
46.8 
47.6 
52.5 
55.7 
53.0 
50.9 
44.8 
49.0 
51.1 



2.34 
2.10 
2.54 
2.76 
3.01 
2.77 
2.68 
2.30 
2.72 
2.73 
2.84 
2.56 



2.14 
1.90 
2.49 
2.58 
3.00 
2.76 
2.49 
2.20 
2.66 
2.50 
2.67 
2.44 



4.48 
4.00 
5.03 
5.34 
6.01 
5.53 
5.17 
4.50 
5.38 
5.23 
5.51 
5.00 



1.09 
1.11 
1.02 
1.07 
1.00 
1.00 
1.08 
1.05 
1.02 
1.09 
1.06 
1.05 



215 



1.25 



51.6 



2.61 



2.49 



5.10 



1.05 



Reduction of Magnetic Data 

The Section of Observatory-Work con- 
tinued the reduction of the magnetic data 
from Watheroo and Huancayo observatories. 
Final reductions were accomplished for the 
year 1938. Work is now progressing on cur- 
rent magnetic records for 1939 and 1940. 

The final values of the magnetic elements 
for all days during 1938 and the preliminary 
values during 1939 for the Watheroo and 
Huancayo observatories are shown in table 9. 

Reduction of Atmospheric-Electric and 
Geoelectric Data 
Scalings of average hourly deflections and 
computations of monthly scale-values were 



tive and negative conductivity varies with 
deflection, whereas that for potential-gradient 
is independent of deflection except for a small 
part of the time; (c) an increase of temper- 
ature of i° C increases the scale-value about 
1 per cent for both conductivity-apparatus. 
This is about the same as the temperature- 
coefficient found for the equipment used at 
Watheroo, Huancayo, and College, and on 
the Carnegie. Because of the good thermal 
insulation of the atmospheric-electric observa- 
tory at Tucson, the diurnal range in temper- 
ature inside, as well as other short-period 
changes, is so small that only the corrections 
for the variation of temperature from month 
to month are important. 



DEPARTMENT OF TERRESTRIAL MAGNETISM 



103 



The final checking, reduction, and com- 
pilation of the earth-current tabulations were 
kept current by Rooney. More revision was 
required than usual. At Watheroo defective 
insulation on one of the lines necessitated the 
scaling of all days for two months of 1938 



from records for the alternate line for the 
same component. At Tucson an undetected 
interchange of the lines between the Observa- 
tory and the distant electrodes necessitated a 
revision of about a quarter of the records 
for 1939. 



Table 9 

Annual Values of the Magnetic Elements at the Watheroo and Huancayo Magnetic 
Observatories as Based upon Magnetograms for All Days, 1938 and 1939 



Decli- 
nation, 
D 



Incli- 
nation, 





Intensity-components 


Hori- 


Total, 
F 


North- 


East- 


zontal, 


south, 


west, 


H 


X 


Y 


(7) 


(7) 


(7) 


(7) 



Vertical, 
Z 

(7) 



Local 

magnetic 

constant, 

G 



Watheroo Magnetic Observatory 



1938 

1939 


3° 26.'3 W 
3 21.0 W 


64° 23.'3 S 
64 23.7 S 


24682 
24687 


57100 
57127 


24638 
24645 


-1480 
-1442 


-51489 
-51517 


35665 
35678 



Huancayo Magnetic Observatory 



1938 

1939 


7 04.6 E 
7 00.4 E 


2 15.6 N 
2 15.1 N 


29572 
29553 


29595 
29586 


29346 
29332 


3643 
3605 


1167 
1162 


29577 
29559 



REDUCTIONS OF CARNEGIE DATA 



Final revisions of manuscripts for three 
volumes of physical, chemical, and biological 
results obtained during the last cruise of the 
Carnegie are under way. Unfortunately, 
limited personnel and the urgency of other 
parts of the Department's program, especially 



the development of the Cyclotron Laboratory 
and its equipment, slowed progress on these 
manuscripts. The numerous diagrams and 
tabulations have been completed for offset 
reproduction. 



INSTRUMENT-SHOP 



The work of the instrument-shop totaled 
approximately 12,800 man-hours by Steiner 
(in charge), instrument-makers Lorz, Haase, 
Huff, Roes (from February 5, 1940), and 
A. M. Schmidt, carpenter A. Smith, and 
apprentice Fogel. This included the construc- 
tion of new equipment and experimental 
apparatus, repairs and improvements of in- 
struments, apparatus, buildings, and grounds, 
and stock, special, and miscellaneous items. 

The major projects were the primary stand- 
ard of the electromagnetic measuring device, 



experimental ionospheric apparatus, improve- 
ments to main building and Experiment 
Building, miscellaneous packing, and im- 
provements, cleaning, and repairs to shop. 

The primary standard required complete 
machining of all the duralumin castings, 
leaving only the various smaller parts to be 
constructed, such as bearings for rotating coil, 
rotating-coil drive-mechanism, and electrical 
connections from both the rotating and the 
primary coils. Special measuring devices were 
made, including an invar ring for supporting 



104 



CARNEGIE INSTITUTION OF WASHINGTON 



the special micrometers, complete metal 
shielding around coil and appurtenances from 
body radiation during measurements, and 
spherical-ended pyrex length-standard. The 
Edelmann base for the primary standard was 
completely rebuilt and all magnetic parts 
were replaced. Difficulty was experienced in 
obtaining sound nonmagnetic brass castings 
from commercial foundries, and it was neces- 
sary to use the Department's small foundry. 
It was found essential that virgin metals be 
used in alloying nonmagnetic brass, since 
the contents must be known precisely. The 
conventional method of foundry practice was 
followed, using a thick covering of charcoal 
over the surface of the copper to prevent the 
copper from oxidizing, and, when the copper 
becomes molten, adding the lead, tin, and 
zinc, stirring with a transite stirring rod, and 
pouring at a temperature between 1825 and 
1875 F. 

A third ionospheric equipment was com- 
pleted. A special high-speed driving mecha- 
nism was made for use at Kensington 
during the eclipse of April 7, 1940, and 
was then disassembled and shipped to the 
Huancayo Magnetic Observatory for use 



during the eclipse of October 1, 1940. A 
visual frequency-band indicator was also con- 
structed. Other ionospheric apparatus in- 
cluded: new cam layout and calibrating 
device; scaling glasses and three scaling-glass 
supporting frames for ionospheric traces. 
Experience with the three equipments at the 
observatories and at Kensington showed that 
an improved design of the band-switch con- 
tactors was desirable; contactors of the new 
design were made, as also other replacement 
parts requested by the observatories. 

Galvanometers 38X to 45X were improved 
by new alnico magnet-systems; Schulze earth- 
inductor 2 and galvanometer 28A, belonging 
to the Apia Observatory, were overhauled; 
alterations were made to the precision cosmic- 
ray meter at Cheltenham; instruments were 
put in order for the First Expedition of the 
U. S. Antarctic Service; a specially designed 
ionization-chamber was made for the Guate- 
malan Volcanological Expedition. Other 
items included equipment for Atomic-Physics 
Observatory and cyclotron; shipments for 
observatories and cooperating organizations; 
development of, and special type for, auto- 
matic justifying typewriter. 



MISCELLANEOUS ACTIVITIES 



Members of the staff took active part as 
delegates and officers in scientific meetings 
and organizations and on numerous special 
committees. Among these were: Seventh 
(triennial) Assembly of the International 
Union of Geodesy and Geophysics, at Wash- 
ington; Sixth Pacific Science Congress, at 
Berkeley and San Francisco; conventions of 
the American Institute of Electrical Engineers 
and Institute of Radio Engineers, at Swamp- 
scott and Boston; Executive Board of the 
International Union of Scientific Radioteleg- 
raphy; Wave-Propagation Committee of the 
Institute of Radio Engineers; American Geo- 
physical Union, at Washington; National 
Advisory Committee on Aeronautics; Ameri- 
can Physical Society; Philosophical Society of 
Washington. Active share was taken in 
several physics colloquia in and near Wash- 
ington. Notes regarding lectures and ad- 



dresses will be found in the section on 
"Publications" given for each branch of work. 

Preparations for, and successful realization 
of, the Washington Assembly of the Inter- 
national Union of Geodesy and Geophysics, 
in September 1939, required much effort and 
time on the part of a number of the staff, 
who undertook the responsibility for the 
extensive office arrangements necessary at 
this Assembly of 719 delegates and guests 
from twenty-six nations and from the United 
States. The meetings of the Union and of 
its seven Associations were devoted almost 
exclusively to the presentation and discussion 
of 492 scientific reports and papers and the 
consideration of resolutions pertaining to the 
progress of geophysics on a coordinated basis 
in all parts of the world. 

Since May 1940, an increasing portion of 
the time of many of the staff has been given 



DEPARTMENT OF TERRESTRIAL MAGNETISM 



105 



to questions of national defense, particularly 
as regards applications of specialized knowl- 
edge to the solution of certain problems. 
These services and use of the facilities of the 
Department have been provided without cost 
to the government. 

Attention was given to plans for, and 
preparation of equipment to be loaned to, 
the National Geographic Society-University 
of Virginia Expedition to the South Sea 
Islands. Active part was taken in the success- 
ful effort to have one of the cutters of the 
U. S. Coast Guard assigned for the use 
of the expedition for one year. Unfor- 
tunately the outbreak of war in Europe made 
it necessary to postpone this geophysical 
survey. 

Exhibit. The Department's contributions 
to the annual exhibition of scientific work of 
the Institution were: (a) the Earth's magnet- 
ism and its long-time or secular changes; 
(b) high-energy transmutation of uranium 
atoms, uranium fission, and radioactive 
tracers; and (c) cosmic rays, in part. The 
first was constructed by the Museum of 
Science and Industry in New York following 
detailed plans and specifications furnished by 
the Department (McNish and Vestine); in- 
cluded was a model showing the representa- 
tion of the Earth's field and its secular vari- 
ation by clusters of dipoles at appropriate 
depths and positions. The second (Tuve and 
associates) demonstrated the effects of radio- 
active tracers resulting from the uranium- 
fission process and their potential value for 
radically new experiments in biology. The 
third was sponsored by the Institution's 
Committee on Coordination of Cosmic-Ray 
Investigations and was planned by Research 
Associate T. H. Johnson and constructed by 
the Bartol Foundation of the Franklin Insti- 
tute with some help from the Department. 

Library. The effect of the outbreak of 
hostilities in Europe early in the report-year 
was reflected in the decrease of publication 
abroad and in the difficulties encountered in 
the procurement of books and journals from 
most of the countries involved. Despite these 
unfavorable conditions, accessions during the 
year amounted to 409, bringing the number 
of accessioned books and pamphlets to 25,761. 



The indexing of publications received and of 
articles of interest in current scientific jour- 
nals, numbering about 100, as set forth in 
previous reports, was continued. 

Librarian Harradon edited contributions in 
foreign languages and contributed letters, 
notes, abstracts, and the quarterly lists of 
recent publications to the journal of Terres- 
trial Magnetism and Atmospheric Electricity. 
Much translation was done, chiefly in con- 
nection with the meeting of the International 
Union of Geodesy and Geophysics. In col- 
laboration with G. E. Boesch and A. Girard, 
Jr., a guidebook of Washington and the pro- 
gram of the Assembly were translated into 
French. 

Scientific papers by members of the staff 
through 1940 totaled 1940. Reprints of pub- 
lished articles were mailed from time to time 
to interested institutions and individuals. 
This distribution was in charge of Dove. A 
large number of reports and manuscripts 
were typed by Dove, who also acted as, secre- 
tary to the Director and continued in charge 
of the general correspondence files. 

As in the past, the facilities of the library 
were extended to investigators and students 
from various institutions and governmental 
bureaus. Interlibrary loans have been made 
with other libraries and cordial and reciprocal 
relations have been maintained, particularly 
with the Library of Congress. 

Office administration. The usual corre- 
spondence, placing of orders, and matters 
concerned with accounting — all in charge of 
M. B. Smith, Administrative Assistant — were 
considerably increased during the year be- 
cause of the construction of the cyclotron 
building and its equipment and because of 
matters relating to the Institution's Com- 
mittee on Coordination of Cosmic-Ray In- 
vestigations. Various matters in connection 
with the meetings of the International Union 
of Geodesy and Geophysics were looked after. 
Through the courtesy of the U. S. Coast 
Guard, it was possible to ship to the Godhavn 
Observatory, in Greenland, cosmic-ray sup- 
plies as well as magnetograph supplies and 
chemicals which could not be forwarded as 
usual from Copenhagen. 

Effective assistance was received as usual 



to6 



CARNEGIE INSTITUTION OF WASHINGTON 



from Moats and Singer (resigned April 9, 
1940), from Dove, and from the newly ap- 
pointed stenographers and typists, Miss D. N. 
Gottshall (from September 20, 1939) and 
Miss R. C. Dermody (from March 25, 1940). 
Capello, property-clerk and stenographer, had 



charge of shipments and inventory and pre- 
pared many manuscripts. Numerous illustra- 
tions, drawings, charts, and sketches for 
articles, lantern-slides, and exhibits were pre- 
pared by Hendrix. The photographic work 
required was done by Ledig. 



BIBLIOGRAPHY 



Abelson, P. H. The identification of character- 
istic X-rays associated with radioactive decay. 
Phys. Rev., vol. 56, pp. 753-757 (1939) . 

See McMillan, E. 

Adams, W. S., J. A. Fleming, and F. E. Wright. 
Progress report of Committee on Coordina- 
tion of Cosmic-Ray Investigations for the 
period July 1938 to June 1939. Carnegie Inst. 
Wash. Year Book No. 38, pp. 335-339 

(i939)- 

Appleton, E. V., and L. V. Berkner. Joint com- 
mittee of the Association of Terrestrial Mag- 
netism and Electricity for collaboration with 
International Scientific Radio Union. First 
report to the Seventh General Assembly at 
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phys., Assoc. Terr. Mag. and Elec, Bull. No. 
n, pp. 292-297 (1940). 

Barry, J. G. See report of Committee on Co- 
ordination of Cosmic-Ray Investigations, 
Carnegie Inst. Wash. Year Book No. 39, 
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Bartels, J. Potsdamer erdmagnetische Kennzif- 
fern. 4. und 5. Mitteilung. Ztschr. f. Geo- 
physik, vol. 15, pp. 214-221, 333-335 (1939)- 

Some problems of terrestrial magnetism 

and electricity. In Physics of the Earth, 
vol. 8, Terrestrial magnetism and electricity, 
pp. 385-433. New York, McGraw-Hill Book 
Co. (1939). 

Erdmagnetismus in Beziehung zu Er- 

scheinungen auf der Sonne. Cinquieme Rap- 
port, Comm. Relations Solaires et Terrestres 
(Firenze), pp. 116-117 (1939). French 
translation, ibid., pp. 118-119. 

Das Nordlicht vom 24.-25. Februar 

1939 in Deutschland und die erdmagne- 
tischen Storungen in Niemegk. Beitr. z. 
Geophysik, vol. 55, pp. 193-203 (1939). 

Zur Frage der hypothetischen die 

Erdoberflache durchdringenden elektrischen 
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(i939)- 

Deutscher Landesbericht. (Abstract) 

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(1940). 

Geophysikalisches Institut, Potsdam. 



Trans. Washington meeting, Sept. 1939; 
Internat. Union Geod. and Geophys., Assoc. 
Terr. Mag. and Elec, Bull. No. 11, pp. 85-86 
(1940). 

— Bestimmung taglicher internationaler 
erdmagnetischer Charakterzahlen fur Jahre 
vor 1890. Trans. Washington meeting, Sept. 
1939; Internat. Union Geod. and Geophys., 
Assoc. Terr. Mag. and Elec, Bull. No. 11, 
pp. 183-195 (1940). 

— N. H. Heck, and H. F. Johnston. The 
three-hour-range index measuring geomag- 
netic activity. Terr. Mag., vol. 44, pp. 411- 

454 (i939)- 

— and H. F. Johnston. Main features of 
daily magnetic variations at Sitka, Chelten- 
ham, Tucson, San Juan, Honolulu, Huan- 
cayo, and Watheroo. Terr. Mag., vol. 44, 

PP- 455-469 (i939)- 
See Chapman, S. 



Berkner, L. V. The nature of radio fade-out. 
Jour. Applied Phys., vol. 10, pp. 532-533 

The nature of radio fade-outs and their 

relation to bright chromospheric eruptions. 
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laires et Terrestres (Firenze), pp. 76-84 

(i939)- . 

Radio exploration of the Earth's outer 

atmosphere. In Physics of the Earth, vol. 8, 
Terrestrial magnetism and electricity, pp. 
434-491. New York, McGraw-Hill Book Co. 

(i939)- 

Observatory technique of ionospheric 

measurements. Trans. Washington meeting, 
Sept. 1939; Internat. Union Geod. and Geo- 
phys., Assoc. Terr. Mag. and Elec, Bull. 
No. 11, pp. 417-437 (1940)- 

Problems of upper atmospheric physics. 

(Abstract) Trans. Washington meeting, 
Sept. 1939; Internat. Union Geod. and Geo- 
phys., Assoc Terr. Mag. and Elec, Bull. 
No. 11, pp. 500-502 (1940). 

H. W. Wells, and S. L. Seaton. Iono- 
spheric effects associated with magnetic dis- 
turbances. Terr. Mag., vol. 44, pp. 283-311 

(i939)- 

See Appleton, E. V.; Seaton, S. L. 



Booker, H. G., and S. L. Seaton. Relation be- 
tween actual and virtual ionospheric height. 
Phys. Rev., vol. 57, pp. 87-94 (1940). 



DEPARTMENT OF TERRESTRIAL MAGNETISM 



107 



Booker, H. G., and S. L. Seaton. Relation be- 
tween actual and virtual ionospheric height. 
Trans. Washington meeting, Sept. 1939; 
Internat. Union Geod. and Geophys., Assoc. 
Terr. Mag. and Elec, Bull. No. 11, pp. 503- 
515 (1940). 

Breit, G., C. Kittel, and H. M. Thaxton. Note 
on p-wave anomalies in proton-proton scat- 
tering. Phys. Rev., vol. 57, pp. 255-259 
(1940). 

and E. Teller. Metastability of hydro- 
gen and helium levels. Astrophys. jour., 
vol. 91, pp. 215-238 (1940). 

See Hoisington, L. E.; Kittel, C. 



Chapman, S. United States geophysical expedi- 
tion to the Pacific Ocean. Nature, vol. 144, 
p. 182 (1939). 

Spectroscopic and other evidence as to 

chemical composition and dissociation [in 
the Earth's atmosphere]. Quart. Jour. Roy. 
Meteorol. Soc, vol. 65, pp. 310-313 (1939). 

Notes on atmospheric sodium. Astro- 
phys. Jour., vol. 90, pp. 309-316 (1939). 

International Union of Geodesy and 

Geophysics. Nature, vol. 144, pp. 717-718 

(i939)- 

Two new books on terrestrial magnet- 
ism and electricity: a review and a preview. 
Terr. Mag., vol. 44, pp. 383-388 (1939). 

The lunar tide in the atmosphere. 

(Abstract) Meteorol. Mag., vol. 74, pp. 273- 
281 (i939)- 

Solar influences on the Earth's mag- 

' netism and on the upper atmosphere. Cin- 

quieme Rapport, Comm. Relations Solaires 
et Terrestres (Firenze), pp. 111-115 (1939). 

Report on international collaboration to 

advance the study of the Moon's effect upon 
geophysical phenomena. Trans. Washington 
meeting, Sept. 1939; Internat. Union Geod. 
and Geophys., Assoc. Terr. Mag. and Elec, 
Bull. No. 11, pp. 297-299 (1940). 

and J. Bartels. Geomagnetism. 2 vols. 



vol. I, pp. xxv + 542; vol. II, pp. x + 543- 
1049 + T1-T77. Oxford, Clarendon Press 
(1940). 

— and T. G. Cowling. The mathematical 
theory of non-uniform gases. An account of 
the kinetic theory of viscosity, thermal con- 
duction, and diffusion in gases, xxiii + 404 
pp. Cambridge, University Press (1939). 

— and J. C. P. Miller. The statistical de- 
termination of lunar daily variations in 
geomagnetic and meteorological elements. 
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Suppl., vol. 4, pp. 649-669 (1940). 

See la Cour, D. 



Coile, R. C. See Wells, H. W. 

Compton, A. H. See report of Committee on 
Coordination of Cosmic-Ray Investigations, 
Carnegie Inst. Wash. Year Book No. 39, 
pp. 120— 121 (1940). 



Cowling, T. G. See Chapman, S. 

Davies, F. T. Principal magnetic storms, Huan- 
cayo Magnetic Observatory, April to June, 
1939; July to September, 1939. Terr. Mag., 
vol. 44, pp. 357-358> 491-492 (1939). 

and G. R. Wait. Densities of condensa- 
tion-nuclei over the North Atlantic Ocean. 
Trans. Washington meeting, Sept. 1939; 
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Terr. Mag. and Elec, Bull. No. 11, pp. 457- 
459 O940). 

Fano, U. A theory of excitation of phospho- 
rescence by cathode rays. (Abstract) Phys. 
Rev., vol. 57, p. 564 (1940). 

Fleming, J. A. Procedure at meetings of the 
International Association of Terrestrial Mag- 
netism and Electricity. Trans. Amer. Geo- 
phys. Union, 20th annual meeting, pt. Ill, 

PP- 390-391 (i939)- 

Progress-report on researches in terres- 
trial magnetism and electricity at Depart- 
ment of Terrestrial Magnetism, Carnegie 
Institution of Washington, for the year 
April 1938 to March 1939. Trans. Amer. 
Geophys. Union, 20th annual meeting, pt. 
Ill, pp. 394-397 (i939)- 

Vagaries of the Earth's magnetism. 

(Abstract) Gen. Elec. Rev., vol. 42, p. 419 
(i939)- 

Summary of the year's work, Depart- 
ment of Terrestrial Magnetism, Carnegie 
Institution of Washington. Terr. Mag., vol. 
44, pp. 405-410 (1939). 

Wide-range magnetograph at Washing- 
ton, D. C. Terr. Mag., vol. 45, pp. 213-214 
(1940). 

The great magnetic storm. Scientific 

Monthly, vol. 50, pp. 475-480 (1940). 

Terrestrial magnetism and electricity. 

Amer. Year Book for 1939, pp. 729-735 
(1940). 

Note regarding resolution no. 4, Wash- 
ington Assembly, International Association 
of Terrestrial Magnetism and Electricity. 
Terr. Mag., vol. 45, p. 106 (1940). 

Washington Assembly of the Inter- 



national Union of Geodesy and Geophysics 
and the American Geophysical Union. 
Science, vol. 91, pp. 439-442 (1940). 

— The Earth's magnetism and magnetic 
surveys. In Physics of the Earth, vol. 8, 
Terrestrial magnetism and electricity, pp. 1- 
58. New York, McGraw-Hill Book Co. 

(i939)- 

— Researches of the Department of Ter- 
restrial Magnetism of the Carnegie Institu- 
tion of Washington bearing on solar and 
terrestrial relationships, 1935-1938. Cin- 
quieme Rapport, Comm. Relations Solaires 
et Terrestres (Firenze), pp. 13-23 (1939). 



io8 



CARNEGIE INSTITUTION OF WASHINGTON 



Fleming, J. A. Statement summarizing trans- 
actions of the Washington meeting of the 
International Association of Terrestrial Mag- 
netism and Electricity. Trans. Washington 
meeting, Sept. 1939; Internat. Union Geod. 
and Geophys., Assoc. Terr. Mag. and Elec, 
Bull. No. 11, pp. 10-15 (1940). 

Trends of research in terrestrial magnet- 
ism and electricity. Trans. Washington 
meeting, Sept. 1939; Internat. Union Geod. 
and Geophys., Assoc. Terr. Mag. and Elec, 
Bull. No. 11, pp. 41-61 (1940). 

Report by the Department of Terres- 
trial Magnetism, Carnegie Institution of 
Washington, to the Washington Assembly 
on work done since the Edinburgh As- 
sembly. Trans. Washington meeting, Sept. 
1939; Internat. Union Geod. and Geophys., 
Assoc. Terr. Mag. and Elec, Bull. No. 11, 
pp. 147-161 (1940). 

Report of committee to consider existing 

and desirable distribution of magnetic and 
electric observatories and the better coordina- 
tion of work and publications of existing 
observatories. Trans. Washington meeting, 
Sept. 1939; Internat. Union Geod. and Geo- 
phys., Assoc. Terr. Mag. and Elec, Bull. No. 
11, pp. 196-204 (1940). 

Report of committee for study of rela- 
tions between solar activity and terrestrial 
magnetism. Trans. Washington meeting, 
Sept. 1939; Internat. Union Geod. and Geo- 
phys., Assoc. Terr. Mag. and Elec, Bull. 
No. 11, pp. 224-226 (1940). 

Electric characterization of days used in 

connection with publication of atmospheric- 
electric data from Watheroo and Huancayo. 
Trans. Washington meeting, Sept. 1939; 
Internat. Union Geod. and Geophys., Assoc. 
Terr. Mag. and Elec, Bull. No. 11, pp. 254- 
258 (1940). 

Progress-report of the joint committee 

of the Commission of Terrestrial Magnetism 
and Atmospheric Electricity of the Inter- 
national Meteorological Organization and 
the Association on methods and codes to 
adequately describe magnetic disturbances 
and perturbations. Trans. Washington meet- 
ing, Sept. 1939; Internat. Union Geod. and 
Geophys., Assoc. Terr. Mag. and Elec, Bull. 
No. 11, pp. 286-291 (1940). 

Suggested lines for further investigations 

of upper-air physics. Trans. Washington 
meeting, Sept. 1939; Internat. Union Geod. 
and Geophys., Assoc. Terr. Mag. and Elec, 
Bull. No. 11, pp. 527-531 (1940). 

H. D. Harradon, and J. W. Joyce. 



— E. A. Johnson, and A. G. McNish. 
Palaeomagnetic investigations. (Abstract) 
Trans. Washington meeting, Sept. 1939; 
Internat. Union Geod. and Geophys., Assoc. 
Terr. Mag. and Elec, Bull. No. 11, p. 535 
(1940). 

— (ed). Terrestrial magnetism and elec- 
tricity. Vol. 8 of Physics of the Earth (Na- 
tional Research Council), xii + 794 pp. New 
York, McGraw-Hill Book Co. (1939). 

— (ed). Transactions of the American 
Geophysical Union, twentieth annual meet- 
ing, April 26 to 29, 1939, Washington, D. C. 
Regional meetings, (A) South Pacific area, 
Los Angeles, California, December 16-17, 
1938; (B) North Continental Divide area, 
Spokane, Washington, December 28, 1938. 
4 pts., 740 pp. Washington, D. C, National 
Research Council (1939). 

See Adams, W. S.; Johnston, H. F. 



Flexner, L. B., and R. B. Roberts. The measure- 
ment of placental permeability with radio- 
active sodium. Amer. Jour. Physiol., vol. 
128, pp. 154-159 (i939)- 

Forbush, S. E. See report of Committee on 
Coordination of Cosmic-Ray Investigations, 
Carnegie Inst. Wash. Year Book No. 39, 
p. 124 (1940). 

Gamow, G. Nuclear reactions in stellar evolu- 
tion. Nature, vol. 144, pp. 575-577, 620-622 

(i939)- 
Gish, O. H. Atmospheric electricity. In Physics 
of the Earth, vol. 8, Terrestrial magnetism 
and electricity, pp. 149-230. New York, 
McGraw-Hill Book Co. (1939). 

Report of the committee for the elec- 
trical characterization of days. Trans. Wash- 
ington meeting, Sept. 1939; Internat. Union 
Geod. and Geophys., Assoc. Terr. Mag. and 
Elec, Bull. No. 11, pp. 242-245 (1940). 

First report on coordinated study of 

volcanic phenomena at Santa Maria. Initial 
geoelectric work. Trans. Washington meet- 
ing, Sept. 1939; Internat. Union Geod. and 
Geophys., Assoc. Terr. Mag. and Elec, Bull. 
No. 11, pp. 541-543 (194°)- 

and K. L. Sherman. Analysis of local 

atmospheric-electric phenomena at College, 
Alaska. Terr. Mag., vol. 45, pp. 173-190 
(1940). 

Ionic equilibrium in the tropo- 



Seventh General Assembly of the Association 
of Terrestrial Magnetism and Electricity at 
Washington, D. C, September 4-15, 1939. 
Terr. Mag., vol. 44, pp. 471-479 (1939)- 



sphere and lower stratosphere. Trans. Wash- 
ington meeting, Sept. 1939; Internat. Union 
Geod. and Geophys., Assoc. Terr. Mag. and 
Elec, Bull. No. 11, pp. 474-491 (1940). 

Goranson, R. W., and E. A. Johnson. The at- 
tainment of high hydrostatic pressures. Phys. 
Rev., vol. 57, p. 845 (1940). 

Hafstad, L. R. On the Bartels technique for 
time-series analysis, and its relation to the 
analysis of variance. Jour. Amer. Statistical 
Assoc, vol. 35, pp. 347-361 (1940). 



DEPARTMENT OF TERRESTRIAL MAGNETISM 



109 



Hafstad, L. R. See Heydenburg, N. P. 

Harradon, H. D. Biographical notes and selected 
references. In Physics of the Earth, vol. 8, 
Terrestrial magnetism and electricity, pp. 
679-778. New York, McGraw-Hill Book Co. 

(i939)- 

List of recent publications. Terr. Mag., 

vol. 44, pp. 361-365, 497-504 (1939) ; vol. 45, 

pp. 113-119, 238-243 (1940). 

The fourth centenary of William Gilbert 

of Colchester. Terr. Mag., vol. 45, pp. 97-98 
(1940). 

The Eighth American Scientific Con- 
gress. Terr. Mag., vol. 45, pp. 220-222 
(1940). 

Report of committee on classification of 

magnetic literature. Trans. Washington 
meeting, Sept. 1939; Internat. Union Geod. 
and Geophys., Assoc. Terr. Mag. and Elec, 
Bull. No. 11, pp. 267-271 (1940). 

See Fleming, J. A. 



Heck, N. H. See Bartels, J. 

Heydenburg, N. P., L. R. Hafstad, and M. A. 
Tuve. The scattering of protons by protons, 
III. Phys. Rev., vol. 56, pp. 1078-1091 

(i939)- 

and N. F. Ramsey. Scattering of one- to 

three-mev protons by helium. (Abstract) 
Phys. Rev., vol. 57, p. 1077 (1940). 

and R. B. Roberts. Deuteron-deuteron, 



proton-helium, and deuteron-helium scatter- 
ing. Phys. Rev., vol. 56, pp. 1092-1095 

(i939)- 
Hoisington, L. E., S. S. Share, and G. Breit. 
Effects of shape of potential energy wells 
detectable by experiments on proton-proton 
scattering. Phys. Rev., vol. 56, pp. 884-890 

(i939)- 

Hopkins, R. E. See Johnson, E. A. 

Hulburt, E. O., E. A. Johnson, and M. A. Tuve. 
Problems of the intermediate atmosphere. 
(Abstract) Trans. Washington meeting, 
Sept. 1939; Internat. Union Geod. and Geo- 
phys., Assoc. Terr. Mag. and Elec, Bull. 
No. 11, pp. 526-527 (1940). 

Johnson, E. A. Measurement of small magnetic 
moments. (Abstract) Jour. Wash. Acad. Sci., 
vol. 29, p. 306 (1939). 

Theory of new primary standard of the 

Carnegie Institution of Washington. (Ab- 
stract) Trans. Amer. Geophys. Union, 20th 
annual meeting, pt. Ill, p. 358 (1939). 

Use of a modulated searchlight beam 

to measure stratospheric conditions. (Ab- 
stract) Bull. Amer. Meteorol. Soc, vol. 21, 
pp. 118-119 (1940). 

A possible method of measuring the 

effect of particle emission on the Earth's mag- 
netic field. Trans. Washington meeting, 
Sept. 1939; Internat. Union Geod. and Geo- 



phys., Assoc. Terr. Mag. and Elec, Bull. 
No. 11, pp. 544-547 ( T 94o)- 

— A design for a travelling electromagnetic 
standard. Trans. Washington meeting, Sept. 
1939; Internat. Union Geod. and Geophys., 
Assoc. Terr. Mag. and Elec, Bull. No. 11, 
PP- 325-332 (1940)- 

— and A. G. McNish. Secular change in 
magnetic declination as deduced from 
polarized varve-sediments. (Abstract) Trans. 
Amer. Geophys. Union, 20th annual meet- 
ing, pt. Ill, p. 358 (1939). 

— R. C. Meyer, R. E. Hopkins, and W. H. 
Mock. The measurement of light scattered 
by the upper atmosphere from a searchlight 
beam. Jour. Optical Soc. Amer., vol. 29, 
pp. 512-517 (1939). 

— W. H. Mock, and R. E. Hopkins. The 
limiting sensitivity of the alternating-current 
method of photo-cell-current amplification. 
Jour. Optical Soc. Amer., vol. 29, pp. 506- 

5" 0939)- 

— and W. F. Steiner. Measurement of 
susceptibility of materials used in magnet- 
ometers. Trans. Washington meeting, Sept. 
1939; Internat. Union Geod. and Geophys., 
Assoc. Terr. Mag. and Elec, Bull. No. n, 

PP- 333-339 (1940). 

See Fleming, J. A.; Goranson, R. W.; 



Hulburt, E. O.; McNish, A. G.; Vestine, 
E. H. 

Johnson, T. H. See report of Committee on 
Coordination of Cosmic-Ray Investigations, 
Carnegie Inst. Wash. Year Book No. 39, 
pp. 126-127 ( I 94 )- 

Johnston, H. F. American URSI broadcasts of 
cosmic data, April to June, 1939, with 
American magnetic character-figure C A , May 
to June, 1939; cosmic data, with American 
magnetic character-figure C A , July to Sep- 
tember, 1939; cosmic data, with American 
magnetic character-figure C A , October to 
December, 1939, and summary of C A for 
year 1939; cosmic data, with American mag- 
netic character-figure C A , January to March, 
1940. Terr. Mag., vol. 44, pp. 349-352, 487- 
49i (i939); vol. 45, pp. 99-104, 214-218 
(1940). 

J. A. Fleming, and H. E. McComb. 

Magnetic instruments. In Physics of the 
Earth, vol. 8, Terrestrial magnetism and 
electricity, pp. 59-109. New York, McGraw- 
Hill Book Co. (1939). 

See Bartels, J.; McNish, A. G. 



Joyce, J. W. See Fleming, J. A. 

Kittel, C, and G. Breit. Note on the scattering 

of neutrons by protons. Phys. Rev., vol. 56, 

PP- 744-749 (i939)- 
See Breit, G. 



no 



CARNEGIE INSTITUTION OF WASHINGTON 



Korff, S. A. See report of Committee on Co- 
ordination of Cosmic-Ray Investigations, 
Carnegie Inst. Wash. Year Book No. 39, 
p. 130 (1940). 

Kuper, }. B. H. See Roberts, R. B. 

la Cour, D., and S. Chapman. Report of the 
committee on registration in Iceland of giant 
pulsations. Trans. Washington meeting, 
Sept. 1939; Internat. Union Geod. and Geo- 
phys., Assoc. Terr. Mag. and Elec, Bull. 
No. 11, pp. 263-265 (1940). 

McComb, H. E. See Johnston, H. F. 

McMillan, E., and P. H. Abelson. Radioactive 
element 93. Phys. Rev., vol. 57, pp. 1185- 
11 86 (1940). 

McNish, A. G. The residual magnetization of 
rocks. (Abstract) Jour. Wash. Acad. Sci., 
vol. 29, pp. 306-307 (1939). 

Interpretation of magnetic changes as- 
sociated with bright chromospheric erup- 
tions. Cinquieme Rapport, Comm. Relations 
Solaires et Terrestres (Firenze), pp. 105-110 

(i939)- 

On causes of the Earth's magnetism and 

its changes. In Physics of the Earth, vol. 8, 
Terrestrial magnetism and electricity, pp. 
308-384. New York, McGraw-Hill Book Co. 

(i939)- 

Physical representation of the geomag- 
netic field. (Abstract) Phys. Rev., vol. 57, 
p. 1088 (1940). 

Note on scale-value equation of the 

CIW induction-variometer. Terr. Mag., vol. 
45, pp. 223-224 (1940). 

First report on coordinated study of vol- 
canic phenomena at Santa Maria. Initial 
geomagnetic work. Trans. Washington 
meeting, Sept. 1939; Internat. Union Geod. 
and Geophys., Assoc. Terr. Mag. and Elec, 
Bull. No. 11, pp. 537-540 (1940). 

and E. A. Johnson. Determination of 

the secular variation in declination in New 
England from magnetic polarization of 
glacial varves. Trans. Washington meeting, 
Sept. 1939; Internat. Union Geod. and 
Geophys., Assoc. Terr. Mag. and Elec, Bull. 
No. 11, pp. 339-347 (1940)- 

and H. F. Johnston. Study of the severe 

magnetic storm of April 1938. Trans. Wash- 
ington meeting, Sept. 1939; Internat. Union 
Geod. and Geophys., Assoc. Terr. Mag. and 
Elec, Bull. No. 11, pp. 348-353 (1940). 

See Fleming, J. A.; Johnson, E. A. 



New Zealand Department of Scientific and 
Industrial Research. Apia Observatory: 
Annual report for 1935. 145 pp. Dept. Sci. 
Indust. Res., Wellington, N. Z. (1938). 

Parkinson, W. C. Principal magnetic storms, 
Watheroo Magnetic Observatory, April t 
June, 1939; June to September, 1939; October 
to December, 1939; January to March, 1940. 
Terr. Mag., vol. 44, pp. 358-359, 494 (*939) I 
vol. 45, pp. no, 233-234 (1940). 

and L. S. Prior. The ionosphere at 

Watheroo, Western Australia, January, 
February, and March, 1939; April, May, and 
June, 1939; July to September, 1939; October 
to December, 1939. Terr. Mag., vol. 44, pp. 
341-343, 401-403 (1939); vol. 45, pp. 45- 
47, 169-172 (1940). 

Prior, L. S. See Parkinson, W. C. 

Ramsey, N. F. See Heydenburg, N. P.; Salant, 
E. O.; Van Allen, J. A. 

Roberts, R. B. The splitting of uranium and 
thorium nuclei by neutrons. (Abstract) 
Jour. Wash. Acad. Sci., vol. 29, p. 310 

(i939)- 

and J. B. H. Kuper. Uranium and 

atomic power. Jour. Applied Phys., vol. 10, 
pp. 612-614 (1939). 

See Flexner, L. B.; Heydenburg, N. P. 



Meyer, R. C. See Johnson, E. A. 

Miller, J. C. P. See Chapman, S. 

Millikan, Robert A. See report of Committee 
on Coordination of Cosmic-Ray Investiga- 
tions, Carnegie Inst. Wash. Year Book No. 
39, pp. 131-132 (1940). 

Mock, W. H. See Johnson, E. A. 



Rooney, W. J. Earth-currents. In Physics of the 
Earth, vol. 8, Terrestrial magnetism and 
electricity, pp. 270-307. New York, McGraw- 
Hill Book Co. (1939). 

Variation in earth-current activity with 

the sunspot-cycle. Trans. Washington meet- 
ing, Sept. 1939; Internat. Union Geod. and 
Geophys., Assoc. Terr. Mag. and Elec, Bull. 
No. n, pp. 467-473 (1940). 

Salant, E. O., and N. F. Ramsey. Fast neutron 
collision cross sections of C and H. (Ab- 
stract) Phys. Rev., vol. 57, p. 1075 (1940). 

Sapsford, H. B. Principal magnetic storms, Apia 
Observatory, April to September, 1939; 
October to December, 1939; January to 
March, 1940. Terr. Mag., vol. 44, pp. 492- 
494 0939); vol. 45, pp. 109-110, 231-232 
(1940). 

Seaton, S. L., and L. V. Berkner. Non-seasonal 
behavior of the F-region. Terr. Mag., vol. 44, 

PP- 313-319 0939)- 

See Berkner, L. V.; Booker, H. G. 

Share, S. S. See Hoisington, L. E. 

Sherman, K. L. Atmospheric-electric relations 

in quiet air. (Abstract) Trans. Amer. Geo- 
phys. Union, 20th annual meeting, pt. Ill, 

P- 376 (i939)- 

Total and uncharged nuclei at Wash- 
ington, D. C. Terr. Mag., vol. 45, pp. 191- 
204 (1940). 

See Gish, O. H. 



DEPARTMENT OF TERRESTRIAL MAGNETISM 



III 



Smith, J. H. C. The absorption of carbon dioxide 
by unilluminated leaves. Plant Physiol., vol. 
!5> PP- 183-224 (1940). 

Stanton, H. E. See Wells, H. W. 

Steiner, W. F. See Johnson, E. A. 

Teller, E., and M. A. Tuve. The sixth Wash- 
ington conference on theoretical physics. 
Science, vol. 91, pp. 621-623 (1940). 

See Breit, G. 

Thaxton, H. M. See Breit, G. 

Torreson, O. W. Comment on Professor Oga- 
sahara's paper concerning the potential- 
gradient measurements at Taihoku, Formosa. 
Terr. Mag., vol. 45, pp. 69-70 (1940). 

Instruments used in observations of 

atmospheric electricity. In Physics of the 
Earth, vol. 8, Terrestrial magnetism and 
electricity, pp. 231-269. New York, Mc- 
Graw-Hill Book Co. (1939). 

and G. R. Wait. Some effects of meteor- 
ological disturbances on the electrical condi- 
tion of the lower atmosphere. (Abstract) 
Trans. Amer. Geophys. Union, 20th annual 
meeting, pt. Ill, pp. 376-377 (1939). 

Need for measurements to sup- 
plement observations of potential-gradient 
and of conductivity at atmospheric-electric 
observatories. Trans. Washington meeting, 
Sept. 1939; Internat. Union Geod. and Geo- 
phys., Assoc. Terr. Mag. and Elec, Bull. 
No. 11, pp. 460-466 (1940). 
See Wait, G. R. 



Tuve, M. A. See Heydenburg, N. P.; Hulburt, 
E. O.; Teller, E.; Vestine, E. H. 

Van Allen, J. A., and N. F. Ramsey. A tech- 
nique for counting high energy protons in 
the presence of fast neutrons. (Abstract) 
Phys. Rev., vol. 57, pp. 1069-1070 (1940). 

Vestine, E. H. The potential of the Earth's mag- 
netic secular variation. (Abstract) Trans. 
Amer. Geophys. Union, 20th annual meet- 
ing, pt. Ill, p. 359 (1939). 

Solar relationships and magnetic storms. 

Cinquieme Rapport, Comm. Relations So- 
laires et Terrestres (Firenze), pp. 120-126 

(i939)- 

The disturbance-field of magnetic 

storms. Trans. Washington meeting, Sept. 
1939; Internat. Union Geod. and Geophys., 
Assoc. Terr. Mag. and Elec, Bull. No. 11, 
pp. 360-381 (1940). 

The potential of the Earth's magnetic 

secular variation. Trans. Washington meet- 
ing, Sept. 1939; Internat. Union Geod. and 
Geophys., Assoc. Terr. Mag. and Elec, Bull. 
No. 11, pp. 382-391 (1940). 

M. A. Tuve, and E. A. Johnson. Various 

hypotheses regarding the origin and mainte- 
nance of the Earth's magnetic field. Trans. 
Washington meeting, Sept. 1939; Internat. 
Union Geod. and Geophys., Assoc Terr. 



Mag. and Elec, Bull. No. 11, pp. 354-360 
(1940). 

Wait, G. R. Ionization and air conditioning. 
Architect. Rec, vol. 86, p. 79 (1939). 

Report on possible errors in connection 

with the use of ion-counters. Trans. Wash- 
ington meeting, Sept. 1939; Internat. Union 
Geod. and Geophys., Assoc. Terr. Mag. and 
Elec, Bull. No. 11, pp. 300-302 (1940). 

and O. W. Torreson. Recombination of 

ions from gas flames. (Abstract) Phys. Rev., 
vol. 57, p. 1071 (1940). 

Some meteorological effects and 

their relation to the electrical condition of 
the lower atmosphere. Trans. Washington 
meeting, Sept. 1939; Internat. Union Geod. 
and Geophys., Assoc. Terr. Mag. and Elec, 
Bull. No. 11, pp. 491-499 (1940). 

See Davies, F. T.; Torreson, O. W. 



Wells, H. W. The ionosphere at Huancayo, 
Peru, April, May, and June, 1939; July to 
September, 1939. Terr. Mag., vol. 44, pp. 
395-399 (1939); vol. 45, pp. 49-52 (1940). 

Principal magnetic storms, Huancayo 

Magnetic Observatory, October to December, 
1939; January to March, 1940. Terr. Mag., 
vol. 45, p. 109, 229-231 (1940). 

and R. C. Coile. The ionosphere at 

Huancayo, Peru, October to December, 1939. 
Terr. Mag., vol. 45, pp. 155-158 (1940). 

■ Ionospheric characteristics at 

Huancayo, Peru, for the year 1939. Terr. 
Mag., vol. 45, pp. 159-165 (1940). 

and H. E. Stanton. The ionosphere at 

Huancayo, Peru, January, February, and 
March, 1939. Terr. Mag., vol. 44, pp. 321- 

3 2 5 (i939)- 

Ionospheric characteristics at 

Huancayo, Peru, December, 1937, through 
December, 1938. Terr. Mag., vol. 44, pp. 

3 2 6-334 (!939)- 

See Berkner, L. V. 



Wright, F. E. See Adams, W. S. 

Reviews 

Chapman, S. Physics of the Earth, vol. 8, Ter- 
restrial magnetism and electricity, edited by 
J. A. Fleming. (Rev.) Quart. Jour. Roy. 
Meteorol. Soc, vol. 66, pp. 92-93 (1940). 

Physics of the Earth, vol. 8, Terrestrial 

magnetism and electricity, edited by J. A. 
Fleming. (Rev.) Nature, vol. 145, pp. 47-48 
(1940). 

Harradon, H. D. Transactions of the American 
Geophysical Union, twentieth annual meet- 
ing, April 26 to 29, 1939, Washington, D. C; 
regional meetings, Los Angeles, California, 
December 16 to 17, 1938, and Spokane, 
Washington, December 28, 1938, edited by 
J. A. Fleming. (Rev.) Terr. Mag., vol. 44, 
pp. 381-382 (1939). 



112 



CARNEGIE INSTITUTION OF WASHINGTON 



Torreson, O. W. The effects of thunderstorms 
and lightning discharges on the Earth's elec- 
tric field, by T. A. Wormell. (Rev.) Terr. 
Mag., vol. 45, pp. 93-94 (1940). 

Vestine, E. H. Electromagnetic induction in 
non-uniform conductors, and the determina- 
tion of the conductivity of the Earth from 
terrestrial-magnetic variations, by B. N. 
Lahiri and A. T. Price. (Rev.) Terr. Mag., 
vol. 45, pp. 95-96 (1940). 



Swedish Polar-Year Expedition, Svea- 

gruvan, Spitzbergen, 1932-1933: General 
introduction, terrestrial magnetism. (Rev.) 
Terrestrial Magnetism, vol. 44, p. 378 

(i939)- 
Wait, G. R. Atmospheric condensation-nuclei, 
by H. Landsberg. (Rev.) Terr. Mag., vol. 
44, PP- .345-346 (i939); Bull- Amer. Me- 
teorological Society, vol. 21, pp. 130—132 
(1940). 



SPECIAL PROJECTS: TERRESTRIAL SCIENCES 

Committee on Coordination of Cosmic-Ray Investigations. Progress report for the period 
July 1939 to June 1940. (For previous reports see Year Books Nos. 32-38.) 



The formation, purposes, and policies of 
the Committee on Coordination of Cosmic- 
Ray Investigations of the Institution are given 
in detail in Year Book No. 38 (pp. 335—349). 
As heretofore, the Committee has enjoyed the 
privilege of consultation during the past year, 
either through personal contacts or through 
correspondence, with the many interested in- 
vestigators in all parts of the world who are 
listed in that report. 

Statements evaluating cosmic-ray research 
were solicited from many capable and dis- 
tinguished American men of science who 
have given much time, effort, and service to 
this field. The following condensed state- 
ment is based upon the judgment of the 
members of the Committee and upon these 
communications. 

The study of cosmic radiation offers an 
effective approach to the investigation of the 
atomic nucleus and is one of the few major 
means of determining relations between 
fundamental physical entities — electrons, mes- 
ons (mesotrons), and protons; that is, the 
basic structure of matter. The results on the 
distribution of cosmic-ray energies, indicat- 
ing the association to some extent of maxima 
and minima of the energy-curve with the 
most abundant elements, are fundamental, 
and the verification or refutation of these is 
of first importance. The conclusions already 
drawn as to the electrical character of cosmic 
rays, the effects of magnetic field and of 
magnetic storms, solar effects, and possible 
origin in our own galaxy, and the discovery 
of the meson as a secondary radiation pro- 
duced in the upper air have stimulated in 
remarkable degree development of special 
apparatus and of associated techniques — 
cloud-chambers, tube-counters, radiosondes, 
equipment for flights in the stratosphere, and 
many others; these, in themselves, represent 
a profitable return for the funds and services 



that have been devoted to research in cosmic 
radiation. 

The Committee since its organization has 
stressed that side of research calling for 
world-wide cooperation, for example, the re- 
cording and discussion of time-variations over 
long periods as an approach which must give, 
and has already given, evidence of cosmical 
interrelations and of the composition of cos- 
mic radiations. These developments and 
potentialities have attracted many men of 
unusual qualifications and ability and of all 
nationalities, so that now over a hundred 
investigators of highest attainments and many 
assistants are devoting their time to this 
subject. Among these we are especially for- 
tunate in having so many representing our 
foremost universities and research institu- 
tions. Already hundreds of important con- 
tributions have been made as a result of the 
support given by these organizations and by 
the Committee through the Carnegie Corpo- 
ration of New York and the Carnegie Insti- 
tution of Washington. Special grants have 
also been stimulated from organizations such 
as the American Philosophical Society, and 
funds, as well as services, have been gener- 
ously contributed by various universities, in- 
cluding, among others, the University of 
Chicago, the California Institute of Tech- 
nology, and the Bartol Research Foundation. 
In all these the Carnegie Corporation of New 
York, through the Carnegie Institution of 
Washington, and the latter itself, in the 
pioneer work of the Department of Terres- 
trial Magnetism over the seas, have taken a 
prominent part not only in providing funds 
but also in providing services. 

An important step in the program spon- 
sored by the Committee has been the im- 
proved treatment of data at the Department 
of Terrestrial Magnetism on a sound sta- 
tistical basis, as regards both regular and 



"3 



ii4 



CARNEGIE INSTITUTION OF WASHINGTON 



irregular time-variations and world-wide 
variations in cosmic radiation. Unique fea- 
tures resulting from this treatment are the 
evidence afforded by the material for critical 
discussion of the possibility of a permanent 
solar magnetic field, and the evidence for 
the existence of current-systems far outside 
the Earth's atmosphere during magnetic 
storms. 

Under the existing disturbed conditions in 
the world we may not look too far ahead, 
but should do everything possible, consistent 
with the demand upon scientific personnel 
in connection with problems of national de- 
fense, to insure that we may not too greatly 
sacrifice future research interests in the field 
of cosmic rays for the immediate present. 
The provision for keeping alive such investi- 
gations of cosmic radiation may be expected 
to yield results second to none in importance 
in the advance on the frontiers of the physical 
sciences and in the understanding of complex 
cosmical phenomena. 

The following summary and appended re- 
ports give details of the year's results and 
progress. 

Instruments. The Carnegie Institution's 
precision recording cosmic-ray meters con- 
tinued operating at the following stations: 
Cheltenham Magnetic Observatory of the 
U. S. Coast and Geodetic Survey, meter C-i, 
George Hartnell in charge; Huancayo (Peru) 
Magnetic Observatory of the Institution's De- 
partment of Terrestrial Magnetism, meter 
C-2, H. W. Wells in charge; National Astro- 
nomical Observatory of Mexico at Teoloyu- 
can, D. F., meter C-4, Dr. Joaquin Gallo in 
charge; Amberley Branch of the Christchurch 
(New Zealand) Magnetic Observatory of the 
Department of Scientific and Industrial Re- 
search of New Zealand, meter C-5, J. W. 
Beagley in charge; Godhavn (Greenland) 
Magnetic Observatory of the Danish Meteor- 
ological Institute, meter C-6, K. Thiesen in 
charge. 

Installation of meter C-3 at Climax, Colo- 
rado, was again delayed owing to defective 
insulation of the collector-system, which re- 
quired the complete dismantling of the 



ionization-chamber. The instrument has been 
operated at Cheltenham since April 17, 1940, 
for comparison with meter C-i at that station 
before installation at Climax. 

Two of the Millikan-Neher meters were 
loaned for use on the First Expedition of the 
U. S. Antarctic Service. These were operated 
on board the Expedition's vessels during the 
journey to the base. Thereafter one was kept 
in constant recording while the other was 
used in several air flights. 

Investigations. Professor A. H. Compton 
at the University of Chicago was responsible 
for a cosmic-ray symposium, the proceedings 
of which were published as a special number 
of the Reviews of Modern Physics. During 
this year there was completed under his 
guidance a four-year investigation of the 
intensity of cosmic rays on the Pacific Ocean 
by Professor D. H. Loughridge and Paul 
Gast, with the cooperation of the Northland 
Transportation Company between Seattle and 
Juneau. These studies led to a correlation of 
the fact that cosmic radiation is more intense 
in winter than in summer with the difference 
in atmospheric temperature. The production 
of mesons at high altitudes was found to 
increase rapidly with altitude. Among these, 
low-energy mesons are of special interest be- 
cause they are distinguishable in mass and 
ionizing power from electrons. The proper- 
ties of the meson were further determined 
by the use of a large cloud-chamber in a 
powerful magnetic field and through the con- 
tinuation of balloon-experiments. Professor 
Compton's associates also gave considerable 
time to the study of changes in cosmic-ray 
intensity, using chiefly the data obtained from 
the seven model-C recording ionization- 
meters. 

Mr. Forbush continued analysis of the 
world-wide effects at the several stations and 
found excellent agreement between these ef- 
fects for Huancayo and Teoloyucan and be- 
tween those for Cheltenham and Christ- 
church. He also finds a significant difference 
between the general trend in cosmic-ray in- 
tensity at Huancayo and Teoloyucan and 
that at Cheltenham and Christchurch which 
may indicate an important change in the 



SPECIAL PROJECTS: TERRESTRIAL SCIENCES 



"5 



latitude-effect with time. Analysis of the 
27-day waves in cosmic-ray intensity was also 
extended to include the data for 48 complete 
solar rotations at one pair of stations and 
40 complete rotations at another pair. This 
material makes possible a more critical search 
for the existence of a persistent 27-day wave 
in cosmic-ray intensity at high latitudes, the 
existence of which would indicate a per- 
manent solar magnetic field. In 87 out of 
98 cases now available from the data for 
Cheltenham, Huancayo, and Teoloyucan, the 
average cosmic-ray intensity for the five inter- 
national magnetically disturbed days of each 
month, Cd, was less than the average for 
the five magnetically quiet days, Cq. A high 
correlation, +0.90, was found between the 
monthly differences (Cd — Cq) for each pair 
of stations. Mr. Forbush gave full time to 
the reduction, analysis, and interpretation of 
the cosmic-ray data obtained at the Com- 
mittee's five stations. He was assisted 
throughout the report-year by F. R. El- 
dridge, Jr. 

Professor V. F. Hess, of Fordham Uni- 
versity, devoted his attention to meson- 
disintegration and air-mass effects at sea-level 
and to preparations for obtaining a series of 
cosmic-ray measurements on board ship from 
New York to Valparaiso. 

The objectives of the continued research 
by Dr. Thomas H. Johnson, of the Bartol 
Research Foundation, were to obtain further 
evidence of the nature of the primary cosmic 
radiation before its encounter with the Earth's 
atmosphere, to investigate the processes of 
interaction of mesons with matter, to study 
the factors affecting the lifetime of a meson 
before its final spontaneous disintegration 
into an electron, and finally to obtain further 
evidence of the production of mesons by pro- 
tons. These objectives were pursued through 
balloon-flights, coincidence-counter measure- 
ments of the proper life of the meson, and 
studies with a large Wilson cloud-chamber. 
In connection with these objectives, several 
valuable technical developments were made. 

Dr. S. A. Korff, of the Bartol Research 
Foundation, looked after cooperation with 
the U. S. Antarctic Service, and in his report 



gives some preliminary account of the work 
so far done by that Service on its first expe- 
dition. Through radio-balloon observations 
he obtained material for further investigation 
of the generation of soft rays and the influ- 
ence of surrounding matter on measurements 
in the stratosphere. The program of flights 
using counters capable of detecting slow and 
fast neutrons was continued, as were also the 
studies of the properties of proportional 
counters and the production of neutrons by 
cosmic radiation. In the investigation of 
neutron-intensities, he found it necessary to 
standardize neutron-counters and neutron- 
sources. 

Professor R. A. Millikan and his associates 
at the California Institute of Technology 
reported upon the following projects: the 
measurement through 45 balloon-flights in 
India, extending nearly to the top of the 
atmosphere, of the latitude-effect in the equa- 
torial belt; the building of a large cosmic-ray 
cloud-chamber of high resolving power to 
obtain more accurate data on the mass and 
nature of the meson; repetition with modern 
and improved techniques of the Millikan- 
Cameron measurements of the ratio of the 
absorption-coefficients for cosmic rays of air 
and water, in the hope of computing from 
these data the lifetime of the meson; and 
completion of the sea-level measurements be- 
tween Seattle and the Strait of Magellan for 
the study of seasonal effect on cosmic-ray 
intensity at sea-level and the interpretation 
of this effect in terms of the lifetime of the 
meson. 

Dr. M. S. Vallarta at the Massachusetts 
Institute of Technology has undertaken the 
investigation of the motion of cosmic-ray 
particles in the magnetic field of the Earth, 
the theory of magnetic storms, and related 
problems. 

Perhaps the best evidence of the activity 
of the investigators to whom the Committee 
has extended some help during the year may 
be found in the bibliographies which follow 
their reports and show the articles published 
from July 1, 1939 to June 30, 1940. 

As in past years, the Committee has been 
favored by generous assistance on the part 



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CARNEGIE INSTITUTION OF WASHINGTON 



of all of those who have been specifically 
mentioned and many others. Particular 
acknowledgment is to be made to the direc- 
tors and staff-members of the organizations 
which continued to give their facilities for 
the program involving continuous records by 
the precision model-C cosmic-ray meters, 
namely, the Danish Meteorological Institute, 
the National Astronomical Observatory of 
Mexico, the Department of Scientific and 
Industrial Research of New Zealand, the 
United States Coast and Geodetic Survey, 
and the Carnegie Institution of Washington. 

W. S. Adams 

J. A. Fleming, Chairman 

F. E. Wright 

Cosmic-Ray Magnet 

Robert B. Br ode 

University of California, Berkeley, California 

A detailed study by means of models has 
been made for the cosmic-ray magnet. As a 
result of this study, the original plans for 
the use of a 350-kw motor-generator set were 
given up in favor of a more efficient iron- 
yoke magnet. The final design involves the 
use of about 5000 pounds of steel and 3000 
pounds of copper. The magnet is water- 
cooled by layers of copper tubing in the wind- 
ing. The thermal contact is fairly efficient 
between the windings and this water-cooling 
because of the use of square copper wire 
with thin woven-glass insulation. 

All the materials for the construction have 
been ordered and are in the Physics Depart- 
ment shop. Steel yokes for the magnet have 
been machined at a local shipyard and the 
other parts have been machined in our shop. 
The bobbins on which the coils will be wound 
have been finished and the actual winding 
has been begun. 

Measurements made by Mr. Bagley, re- 
search student, on the writer's old magnet 
show considerable scattering due to the un- 
certain curvature in the small magnetic field 
available. However, they indicate a meson- 
mass of the order of magnitude of 100. This 
is considerably smaller than previous esti- 
mates. With ten times the magnetic field in 



the new magnet, these results will be much 
more reliable, and it may be possible to 
identify mesons of more than one mass if 
this should prove to be the cause of the 
scattering. Unpublished results of Dr. Sen 
Gupta, a student of Professor Blackett at 
Manchester, resulting from measurements in 
argon, are in good agreement with the nitro- 
gen measurements at this laboratory. Fermi's 
theory of the influence of the dielectric con- 
stant of the gas should become apparent for 
electrons above io 9 electron-volts and for 
mesons above io 10 electron-volts. It is antici- 
pated that the Carnegie magnet will give 
some information in this energy-region. 

Report on Cosmic-Ray Research at the 
University of Chicago 

A. H. Compton 
University of Chicago, Chicago, Illinois 

Cosmic-ray symposium. The year 1939— 
1940 opened with an international congress 
of students of cosmic rays at the University 
of Chicago. Since the congress under the 
auspices of the Physical Society of London 
in 1934, no comparable gioup of specialists 
in this field had been brought together. The 
discussions gave new impetus to the work of 
the American investigators and summarized 
the results obtained by the European investi- 
gators before most of their studies were 
stopped by the war. 

The chief interest of the members of the 
congress was centered around the use of 
cosmic rays as a tool for investigating the 
properties of the fundamental particles, pro- 
tons, mesons, electrons, neutrinos, etc., and 
the structure of atomic nuclei. It was felt 
that in cosmic rays, because of their very high 
energy, lies our most hopeful approach to 
these problems. Attention was given also to 
such questions as the factors which affect the 
intensity of cosmic rays, the production of 
secondary radiation, and the composition and 
properties of the cosmic-ray particles. The 
proceedings of the congress were published 
as a special number of the Reviews of 
Modern Physics. 



SPECIAL PROJECTS: TERRESTRIAL SCIENCES 



117 



Cosmic rays on the Pacific Ocean. This 
year marked the completion of a four-year 
investigation of the intensity of cosmic rays 
on the Pacific Ocean. During this period, 
almost without interruption, observations 
have been taken with a model-C ionization- 
meter over the route from Tasmania to 
Alaska. The final stage of 16 months' read- 
ings was obtained by Professor D. H. Lough- 
ridge and Paul Gast, with the cooperation of 
the Northland Transportation Company, be- 
tween Seattle and Juneau. This study has 
given a much more detailed knowledge of 
the variation of cosmic rays with latitude, 
from magnetic latitude 53 ° south to 62 ° 
north. 

The immediate occasion for undertaking 
this investigation was to learn whether the 
northerly motion of the Earth through space 
with the rotation of the galaxy gives rise to an 
excess of cosmic rays in the northern hemi- 
sphere. Approximate calculation predicts a 
difference of 0.4 per cent if the rays originate 
beyond the Milky Way. The observations do 
indeed reveal an excess of about this amount; 
but the difference is completely accounted for 
( ±0.1 per cent) by the lower temperature of 
the air in the northern hemisphere along the 
route followed. It thus appears probable that 
the cosmic rays do not come to us from 
beyond the Milky Way. They seem rather 
to share the general motion of our neighbor- 
ing stars. 

Between the equator and 40 ° latitude there 
is an increase in cosmic-ray intensity of about 
10 per cent. Above this latitude, when ac- 
count has been taken of temperature-differ- 
ences, no perceptible further increase occurs, 
[n accord with Lemaitre and Vallarta's theory 
of the action of the Earth's magnetic field on 
electrical particles approaching the Earth, this 
means that primary particles with energies 
of less than six billion electron-volts are not 
able to produce effects that can traverse the 
atmosphere. We have found, however, that 
the primary cosmic rays produce mesons close 
to the top of the atmosphere and that a meson 
loses slightly less than three billion electron- 
volts in passing through this amount of ma- 



terial. Our observation thus supports the 
view that the mesons are produced in pairs 
of roughly equal energy when the primary 
rays enter the upper layers of the atmosphere, 
and that these mesons form the penetrating 
rays which reach the Earth's surface. 

Radioactive disintegration of mesons. In 
our Pacific Ocean studies it was observed that 
in both hemispheres cosmic rays were more 
intense in winter than in summer. Follow- 
ing a suggestion of earlier investigators, this 
difference was correlated with the difference 
in atmospheric temperature. Blackett of Man- 
chester showed how such a dependence on 
temperature should be present if mesons, pro- 
duced high in the atmosphere, should disinte- 
grate with a mean life comparable with the 
time required to reach the ground. Other 
lines of evidence for such disintegration were 
also brought forward. Finally, in an experi- 
ment carried out by Bruno Rossi, on an 
expedition from our laboratory to Mount 
Evans, the existence of such radioactivity of 
the meson was established. 

Rossi counted the mesons received at 
10,000 feet elevation, and then at 14,000 feet 
elevation with a mass of carbon over the 
counter-tubes equivalent in mass to the 4000 
feet of air between the two stations. The 
counting rate at the upper station remained 
considerably greater. This was due to the 
loss of mesons between the two stations as 
they disintegrated en route. The average path 
traversed before disintegration was found to 
be about 6 miles, which means a life of about 
30 microseconds. In a second similar experi- 
ment, in the summer of 1940, measurements 
were made of the life of mesons of such 
relatively low energy that they are stopped 
in about 20 cm of lead. Their life was found 
to be 10 microseconds. According to the 
theory of relativity, the rate of a moving clock 
should be in proportion to its total energy. 
On this basis the life of a meson at rest should 
be close to 2 microseconds. This determina- 
tion of the lifetime of the faster and slower 
mesons constitutes a striking demonstration 
of the variation of rate of a moving clock. 

Production of mesons at high altitudes. 
Since mesons are radioactive, it is evident 



n8 



CARNEGIE INSTITUTION OF WASHINGTON 



that they cannot come to the Earth from great 
distances, but must rather be produced in the 
atmosphere itself. Theories have been de- 
veloped which indicate a high probability of 
production of mesons when protons or neu- 
trons traverse matter, and a somewhat lower 
probability of production by photons or elec- 
trons of very high energy. Our earlier experi- 
ments had shown no appreciable meson- 
production by electrically neutral rays at sea- 
level or even on a mountain at 14,000 feet. 
Airplane experiments by Wilson and Schein 
showed, however, that such meson-production 
by neutral rays does occur at altitudes above 
20,000 feet. During the past year W. P. Jesse, 
Marcel Schein, and E. O. Wollan have sent 
recording counter tubes to very high altitudes 
with balloons to study this phenomenon. 
They find that meson-production increases 
rapidly with altitude, and shows no evident 
diminution even at an atmospheric pressure 
of only 2 cm. At this altitude the number 
of mesons is at least as great as Millikan's 
estimate of the number of incoming primary 
particles. j 

These experiments indicate also the pres- 
ence of many mesons of low energy at high 
altitudes. Such low-energy mesons are of 
especial interest, because they are distin- 
guishable in mass and ionizing power from 
electrons. At sea-level they are exceedingly 
rare. Gerhard Herzog accordingly developed 
a cloud-chamber and a permanent magnet 
suitable for use in an airplane, and with 
W. Bostick made three successful flights. 
The photographs taken between 25,000 and 
30,000 feet show large numbers of slow 
mesons, their production in pairs, and their 
occasional stopping in a thin plate of copper. 

These photographs and similar ones taken 
by Bostick on Mount Evans show evidence 
of an occasional high-speed electron emitted 
from the end of the meson-path. In most 
cases, however, no such electron-track is 
visible. It would thus appear that when a 
meson stops in solid matter the probability 
of its capture by a process that does not give 
rise to the emission of an electrically charged 
ray may be greater than that of radioactive 



disintegration with the emission of an elec- 
tron. Both processes are predicted by 
Yukawa's theory of the meson. 

Properties of mesons. Continuing experi- 
ments begun by Anderson, Blackett, and 
Jones, Donald Hughes has made a new and 
more precise study of the energy-distribution 
of the mesons at ground-level, using a large 
cloud-chamber in a powerful magnetic field. 
The most probable energy is about a billion 
electron-volts, with very few having energies 
less than 0.2 billion, and about 13 per cent 
having energies greater than ten billion 
electron-volts. 

Hughes established what has for some time 
been suspected, that at sea-level positive mes- 
ons exceed negative mesons in number by 
about 25 per cent. The ratio of the numbers 
is nearly independent of the energy-range 
considered. It seems reasonable to relate this 
excess of positives to the well-known excess 
of positive primaries, as shown by the excess 
of cosmic-ray particles coming from the west. 
This lends support to the view that some 
mesons are produced by the direct action of 
protons. 

Balloon experiments by Jesse, Schein, and 
Wollan from Chicago and Texas indicate 
that at high altitudes the latitude-effect on 
mesons is only about a third as great as on 
the soft component of cosmic rays. The dif- 
ference between these two stations is due to 
the primary particles of about five billion 
electron-volts energy which penetrate the 
Earth's magnetic field at Chicago but not at 
Texas. Thus it seems that primaries of this 
energy are relatively more effective in exciting 
the soft component (electrons and photons), 
and that it must be the higher-energy pri- 
maries that give most of the mesons. 

In order to account for a change in the 
slope of his absorption-curve of cosmic rays 
at depths of over 300 feet below ground, 
V. C. Wilson suggested that mesons with 
enough energy to reach these great depths 
may lose energy by radiation, as electrons do 
at lower energies. This hypothesis has been 
supported by certain theoretical calculations. 
Wilson has accordingly carried out counter- 
experiments in tunnels and mines above and 



SPECIAL PROJECTS: TERRESTRIAL SCIENCES 



II 9 



below depths of 300 feet to study the nature 
of the penetrating rays. Though he finds that 
at both depths the counters record highly 
penetrating electrical particles, showers are 
relatively more abundant at the greater 
depths. A cloud-chamber to photograph these 
deeply penetrating particles is now in 
operation. 

Changes in cosmic-ray intensity. Using 
chiefly the data obtained from the seven 
model-C recording ionization-meters that are 
being operated under the joint supervision of 
the Carnegie Institution of Washington and 
the University of Chicago, studies have been 
made of the factors connected with changes 
in the cosmic rays. 

Most striking is the discovery of the major 
importance of the air-distribution in the at- 
mosphere. The correlation with temperature 
pointed in this direction. Loughridge and 
Gast, from data taken on the Pacific Ocean, 
found marked effects caused by the approach 
of cold or warm "fronts." Now, by compar- 
ing the fluctuations of the cosmic rays at sea- 
level at Cheltenham with the changes in 
the meteorological balloon data taken near 
Washington on the same days, N. F. Beards- 
ley finds 10 per cent of the variations are 
associated with those at Huancayo (world- 
wide changes), 15 per cent with changes in 
the barometer (total air-mass), and 40 per 
cent with changes in the vertical distribution 
of the air-mass (caused chiefly by temper- 
ature-changes). A change in the mass of air 
above 12 km is accompanied by more than 
twice as great a change in cosmic rays as is 
the same change in the air-mass near the 
ground. This relatively great importance of 
air-mass at high altitudes is just what is to 
be expected from the rapid disintegration of 
the mesons after they are produced in the 
upper atmosphere, and is in qualitative accord 
with the meson-decay observation of Rossi. 

W. P. Jesse has studied the changes in 
cosmic rays close to the top of the atmosphere, 
by balloon-flights made approximately once 
a month. Such data should be independent 
of atmospheric temperature. The observed 
changes of some 10 per cent follow, however, 
the changes observed at Huancayo, and seem 



to show a seasonal effect with a sharp drop 
in the spring. If further tests show that this 
seasonal effect is real, it may perhaps be 
ascribed to some interaction between the 
magnetic fields of the Earth and Sun. 

Of the possible periodic effects, we recog- 
nize clearly one following the solar day and 
a 28-day period. Changes following the 
sidereal day, or the year-after correction for 
temperature-effects, are relatively small if 
present at all. Special attention has been 
given to the 28-day period. This seems to be 
associated with the Sun's rotation, and if so, 
indicates an action on cosmic rays far outside 
the Earth. 

More complete discussions of these and 
other cosmic-ray experiments carried on in 
our laboratories during the past year are 
given in the publications listed in the bibliog- 
raphy which follows this report. 

Personnel. Our cosmic-ray research is so 
closely integrated that all parts of it have 
profited by cooperation with the Carnegie 
Institution of Washington. The following 
research associates, instructors, and research 
fellows of the University of Chicago have 
given most of their time to this work: W. P. 
Jesse, Marcel Schein, E. O. Wollan, V. C. 
Wilson, Donald J. Hughes, Bruno Rossi, 
Ardis T. Monk, Elmer Dershem, N. F. 
Beardsley, P. S. Gill, and Victor Regener. 
Drs. Gerhard Herzog and Gerhart Groetz- 
inger, as guests of the laboratory, have de- 
voted their time to cosmic-ray studies. As 
graduate students, F. L. Code and Winston 
Bostick have made contributions of special 
value. Particular mention should be made 
of the active aid given to our cosmic-ray 
program by Professor D. H. Loughridge and 
Paul Gast, of the University of Washington; 
Professor Victor F. Hess and his colleagues, 
of Fordham University; Professor J. C. 
Stearns, of the University of Denver; Pro- 
fessors R. D. Bennett and M. S. Vallarta, of 
Massachusetts Institute of Technology; Pro- 
fessor G. R. Tatum, of Baylor University; 
Professor H. V. N. Hilberry, of New York 
University; Dr. John A. Fleming and S. E. 
Forbush, of the Carnegie Institution of Wash- 
ington; Professor Joaquin Gallo, of the Uni- 



120 



CARNEGIE INSTITUTION OF WASHINGTON 



versity of Mexico; and R. N. Turner, of the 
R.M.S. Aorangi. 

Cosmic-ray studies in war time. In plan- 
ning for the continuation of this active pro- 
gram at a time when the nation must gird 
itself for defense, we must note that the study 
of cosmic rays is of no considerable practical 
value. Like astronomy, it is concerned rather 
with the better understanding of the world. 
Nevertheless, we consider this study as second 
to none in human value. The properties of 
the fundamental particles, the study of which 
is a main objective of cosmic-ray investiga- 
tions, present a problem of scientific impor- 
tance strictly comparable with that of the 
structure of atoms or of molecules. That the 
field is newer than chemistry merely indicates 
the greater need for its study. 

Except under the greatest stress, the long- 
time programs of recording cosmic-ray data 
should not be allowed to lapse, for their value 
pyramids with the years. Other important 
projects under way should be completed if 
at all possible. On the other hand, new 
projects in this field can now be undertaken 
only where most urgent. We hope, neverthe- 
less, to be able to keep enough of this work 
going to enable us to begin afresh when the 
way is again clear. 

Bibliography 

Beardsley, Niel F. Correlation between cosmic- 
ray intensity and upper air pressures and 
temperatures. Phys. Rev., vol. 57, pp. 336— 
337 (i94o). 

Blackett, P. M. S., and B. Rossi. Some recent 
experiments on cosmic rays. Rev. Modern 
Phys., vol. 11, pp. 277-280 (1939). 

Compton, A. H. Time variations of cosmic rays. 
Jour. Franklin Inst., vol. 227, pp. 607-620 

(i939)- 
and P. S. Gill. Cosmic rays on the Pacific 

Ocean. Rev. Modern Phys., vol. 11, p. 136 

(i939)- 
Gill, P. S. Further study of cosmic rays on the 

Pacific Ocean. Phys. Rev., vol. 55, pp. 1151- 

1159 (1939); (abstract) Phys. Rev., vol. 

55, pp. iiio-iiii (1939). 

Time distribution of cosmic-ray bursts. 

Phys. Rev., vol. 56, pp. 632-634 (1939). 

East-west asymmetry of cosmic rays at 

40 N. latitude. (Abstract) Phys. Rev., vol. 
57, p. 68 (1940). 



Herzog, G. Search for heavy cosmic-ray particles 

with a cloud-chamber. (Letter) Phys. Rev., 

vol. 55, p. 1266 (1939). 
Cloud-chamber photographs of cosmic 

rays up to an altitude of 29,300 feet. Phys. 

Rev., vol. 57, p. 337 (1940). 

Circuit for anticoincidences with Geiger- 



Miiller counters. Rev. Sci. Instr., vol. n, 
pp. 84-85 (1940). 

Hughes, D. J. Positive excess and electron com- 
ponent in the cosmic-ray spectrum. Phys. 
Rev., vol. 57, pp. 592-597 (1940); (abstract) 
Phys. Rev., vol. 57, p. 356 (1940). 

Janossy, L., and B. Rossi. On the photon compo- 
nent of cosmic radiation and its absorption 
coefficient. Proc. Roy. Soc, A, vol. 175, pp. 
88-100 (1940). 

Jesse, W. P. Time variations in cosmic-ray in- 
tensity at high altitudes. (Abstract) Phys. 
Rev., vol. 57, p. 356 (1940). 

Seasonal studies at high altitudes. Rev. 

Modern Phys., vol. 11, p. 167 (1939). 

Jones, H. Energy distribution and positive ex- 
cess of mesotrons. Rev. Modern Phys., vol. 
11, pp. 235-238 (1939). 

and D. J. Hughes. A magnet and cloud 

chamber for cosmic-ray studies. Rev. Sci. 
Instr., vol. 11, pp. 79—83 (1940). 

Loughridge, D. H, and Paul Gast. Air-mass 

effect on cosmic-ray intensity. (Abstract) 

Phys. Rev., vol. 57, p. 249 (1940). 
Magnetic storm effect on cosmic 

rays at high latitudes. Phys. Rev., vol. 57, 

p. 938 (1940). 
Monk, A. T., and A. H. Compton. Recurrence 

phenomena in cosmic-ray intensity. Rev. 

Modern Phys., vol. 11, pp. 173-179 (1939). 
Rossi, B. The disintegration of mesotrons. Rev. 

Modern Phys., vol. n, pp. 296-303 (1939). 

Electrons arising from disintegration of 

mesotrons. Phys. Rev., vol. 57, pp. 469-471 
(1940). 

System of units for nuclear and cosmic- 
ray phenomena. Phys. Rev., vol. 57, p. 
660 (1940). 

• H. V. N. Hilberry, and J. B. Hoag. Var- 



iation of the hard component of cosmic 
rays with height and disintegration of meso- 
trons. Phys. Rev., vol. 57, pp. 461-469 
(1940); (abstract) Phys. Rev., vol. 57, p. 67 
(1940). 

Schein, M., and P. S. Gill. Burst frequency as 
a function of energy. Rev. Modern Phys., 
vol. 11, pp. 267-276 (1939). 

Cosmic-ray bursts in great thick- 
nesses of lead. (Abstract) Phys. Rev., vol. 55, 
p. mi (1939). 

W. P. Jesse, and E. O. Wollan. Intensity 

and rate of production of mesotrons in the 
stratosphere. Phys. Rev., vol. 57, pp. 847- 
854 (1940). 



SPECIAL PROJECTS: TERRESTRIAL SCIENCES 



121 



Schein, M., and V. C. Wilson. Mesotron pro- 
duction in the atmosphere. Rev. Modern 
Phys., vol. ii, pp. 292-295 (1939). 

Wilson, V. C. Nature of cosmic rays below 
ground. Rev. Modern Phys., vol. 11, pp. 
230-231 (1939). 

Wollan, E. O. Present status of solar and 
sidereal time variation of cosmic rays. Rev. 
Modern Phys., vol. 11, pp. 160-165 (1939). 

Statistical Investigations of 
Cosmic-Ray Variations 

S. E. Forbush 

Department of Terrestrial Magnetism, 

Washington, District of Columbia 

Reduction of data. As in previous years, 
the scalings of hourly values of cosmic-ray 
ionization, bursts, and barometric pressure 
were kept current, together with adequate 
check-measurements by an independent ob- 
server, for the records obtained at Chelten- 
ham, Godhavn, and Huancayo. Reductions 
of daily mean values of ionization to con- 
stant barometric pressure were also kept cur- 
rent for Cheltenham, Christchurch, Godhavn, 
and Huancayo. 

The reductions to constant barometric pres- 
sure of the bihourly mean values of ioniza- 
tion for each day were completed through 
May 1940 for Cheltenham and through Sep- 
tember 1939 for Godhavn. Reduction to 
constant barometric pressure of the bihourly 
means of ionization at Huancayo was also 
begun. 

The barometric coefficients were heretofore 
derived through correlation between daily 
means of ionization and barometric pressure 
for intervals of a month or more. The coeffi- 
cients " thus obtained, for Godhavn and for 
Christchurch, agreed excellently with those 
recently obtained by correlating the bihourly 
means of ionization and of barometric pres- 
sure averaged for each of two groups of 
selected 24-hour intervals. The 24-hour 
intervals in one group were all characterized 
by rapidly increasing barometric pressure, 
those in the other by rapidly decreasing baro- 
metric pressure. No significant difference was 
found between the barometric coefficients de- 
rived from the two groups. Also the baro- 



metric coefficients for Cheltenham, Christ- 
church, and Godhavn were found to agree 
within the statistical uncertainty of about 5 
per cent. Since these three stations are at the 
same elevation and all in high latitudes, there 
is no theoretical reason to expect differences 
in the barometric coefficients. The good agree- 
ment actually found provides a reliable check 
on the absolute sensitivity of the meter at 
these locations. 

By correlating the daily means of ionization 
of barometric pressure averaged for many 
selected periods of a week during which the 
greatest obtainable changes in pressure oc- 
curred, a barometric coefficient for Huancayo 
was obtained in excellent agreement with the 
somewhat less certain value obtained from 
the ratio of the amplitude of the large 12-hour 
solar wave in barometric pressure to that in 
the cosmic-ray ionization without correction 
for pressure. 

Intercomparison of cosmic-ray meters. 
Intercomparison of cosmic-ray meter C-3, 
which the Committee planned to install at 
Climax, Colorado, with meter C-i at Chel- 
tenham was delayed owing to defective insu- 
lation of the collector-system. This was 
caused by direct contact to the collector- 
system of one of the neoprene washers used 
for argon-seals at the ends of the amber 
insulators. This defect necessitated the com- 
plete dismantling of the ionization-chamber 
and the design of retainers to prevent the 
neoprene gaskets from squeezing out of place 
and making contact with the collector-system. 

For reliable performance the insulation- 
resistance of the collector-system should not 
be less than io 10 ohms. To measure reliably 
the insulation-resistance up to io 1G ohms, a 
procedure was devised which could also be 
applied to the meters at the several cosmic- 
ray stations. Using this procedure, the resist- 
ance of the collector-system, after the amber 
insulators had been polished with chamois 
and Putz pomade and washed in ether, de- 
creased from about 5 X io 15 ohms to about 
3X10 14 ohms in 9 days. Since the latter 
value was wholly inadequate, the insulators 
were removed and carefully repolished but 
not washed in ether. Following this treat- 



122 



CARNEGIE INSTITUTION OF WASHINGTON 



ment, the insulation remained unchanged at 
about 2X io 16 ohms for 6 weeks. 

To eliminate inconvenience and uncertain- 
ties in data due to argon slowly escaping from 
the ionization-chamber, even at such a rate 
as could only be detected by readings on the 
argon-pressure gauge over a period of months, 
a vacuum technique was applied which in- 
sured the absence of any argon-leak (except 
at the main gasket where the neck of the 
chamber attaches to the bomb, where no 
difficulty has yet been experienced with any 
of the meters) sufficiently large to cause a 
decrease in argon-pressure as great as one 
pound per square inch per year with the 
initial pressure at 750 pounds per square inch. 

The main ionization-chamber of this bomb, 
which was used at Cheltenham until February 
1937, then had anomalous saturation-charac- 
teristics. Also the ionization was seriously 
affected by changes in temperature. For 
these reasons particular care was taken to 
insure that the geometrical arrangement of 
the collector-system was identical with that 
in other meters. As a result the saturation- 
characteristics of the main chamber and of 
the balance-chamber are now excellent. 

Meter C-3 has been operated continuously 
at Cheltenham since April 17, 1940, for com- 
parison there with meter C-r. The ratio of 
sensitivities of the two meters, calculated 
from carefully measured constants, agreed 
well with that derived from an analysis of 
the observed changes in recorded ionization. 
This ratio also agreed well with that obtained 
from a comparison of the increase in ioniza- 
tion in each of the meters produced by a 
radium sample. 

Statistical analysis of the comparison-data 
obtained since April 17, 1940, indicates a 
systematic change in one of the meters of 
about 1 per cent of the total cosmic-ray 
intensity. Since this change is of the same 
magnitude as the amplitude of the seasonal 
variation, it is essential to determine the 
cause. 

Barograph for Huancayo. At Huancayo 
the 24-hour and 12-hour solar waves in baro- 
metric pressure each have an amplitude of 
about 1 mm of mercury. Thus the corrections 



for barometric pressure to the observed di- 
urnal variation of cosmic-ray intensity are 
especially large and require reliable baro- 
metric-pressure data. Although no serious 
defect exists in the performance of the ordi- 
nary pen-recording barograph from which 
these data are now obtained at Huancayo, a 
more open time-scale, a greater sensitivity, 
and a greater freedom from friction are 
desirable in a barograph. These character- 
istics are also much desired by several investi- 
gators of the lunar-barometric tides. The 
Paulin barograph, originally installed in 
cosmic-ray meter C-2 at Huancayo, but dam- 
aged in transit, has been repaired and care- 
fully compared with a standard barometer 
at the Department. Because of its excellent 
performance it is planned to mount this 
instrument at Huancayo to record photo- 
graphically with an open time-scale and 
sufficient sensitivity. 

Cosmic-ray intensity and magnetic activity. 
That the world-wide changes in cosmic-ray 
intensity are associated with magnetic activity 
is demonstrated by the fact that the cosmic- 
ray intensity is nearly always lowered on days 
of magnetic disturbance. To facilitate descrip- 
tion of the quantitative results obtained as 
evidence of this association, let the average 
cosmic-ray intensity for the five magnetically 
quietest and for the five magnetically most 
disturbed days in each month be designated 
by Cq and Co, respectively, and let D = 
(Cq — Cd)- Using all available data at Chel- 
tenham, Huancayo, and Teoloyucan through 
August 1939, 98 values of D were derived, 
of which 87 were negative with an average 
several times greater in absolute value than 
the average of the 11 positive values. Since 
it is well known that the horizontal com- 
ponent of the Earth's field is always less on 
magnetically disturbed days than on quiet 
days, these changes in cosmic-ray intensity 
are consistent with the hypothesis that the 
changes result from alterations of cosmic-ray 
trajectories produced by the Earth's external 
magnetic-disturbance field. 

Using values of D for each of the same 
25 months at Cheltenham, Teoloyucan, and 
Huancayo, the correlation-coefficient between 



SPECIAL PROJECTS: TERRESTRIAL SCIENCES 



123 



each pair was found to be about +0.90. This 
high correlation provided a determination of 
the ratio of D at each pair of stations, which 
was in approximate agreement with that 
derived from earlier analyses of the world- 
wide changes {Physical Review, vol. 54, p. 
975, 1938). Results of the above investigation 
are soon to be published in the Journal of 
Terrestrial Magnetism and Atmospheric 
Electricity. 

World-wide changes in cosmic-ray in- 
tensity. In a previous investigation (see refer- 
ence above), it was found that if the 
12-month wave in cosmic-ray intensity was 
removed from the data for each station except 
Huancayo, for which the 12-month wave was 
absent, the curves through the resulting 
monthly means were remarkably similar for 
all stations. This investigation has now been 
extended to include all data now available. 
The results indicate no significant change in 
the 12-month waves at any of the stations. 
The curves through the monthly means after 
deducting the 12-month wave are still re- 
markably similar for Huancayo and Teo- 
loyucan, and also for Christchurch and 
Cheltenham. However, a considerable di- 
vergence has occurred between the trend of 
the curves for Huancayo and Teoloyucan 
and that for Christchurch and Cheltenham. 
This divergence may possibly indicate an 
important change in latitude-effect with sun- 
spot-cycle. The latitude-survey which Pro- 
fessor V. F. Hess plans to make using a 
Compton-Bennett meter on board a Grace 
Line steamer from New York to Valparaiso 
should provide data which, together with 
those which have already been obtained by 
Professor A. H. Compton in the Pacific, will 
determine whether any significant change in 
the latitude-effect has occurred at sea-level. 
Results of the recent investigation of world- 
wide effects are expected to be ready for 
publication soon. 

Time-variations in burst-rate at Huancayo. 
A preliminary investigation of the rate of 
production of bursts at Huancayo indicates 
the existence of significant changes in the 
number of bursts per month. These changes 



appear to follow the changes in total cosmic- 
ray intensity from month to month. Attempts 
to determine from the data at hand whether 
significant changes with time occurred in 
the energy-distribution of bursts proved fruit- 
less because of the inevitable uncertainties 
and systematic errors in determining the 
actual size of the smaller bursts, and because 
of uncertainties in the corrections for elec- 
trometer-sensitivity. To facilitate future in- 
vestigations of changes in burst-rate, arrange- 
ments have been made to maintain the elec- 
trometer-sensitivity of the meters constant. 

On the 2j-day variations in cosmic-ray 
intensity. The analysis of the 27-day and 
13.5-day waves in cosmic-ray intensity re- 
ported at the Washington Assembly of the 
International Association of Terrestrial Mag- 
netism and Electricity, September 1939, has 
now been extended to include the following 
number of complete solar rotations at each 
of the following stations: Cheltenham, 40; 
Christchurch, 48; Huancayo, 51. Harmonic 
analysis for each solar rotation has also been 
made for magnetic character-figure for the 
same period and for magnetic horizontal 
intensity at Huancayo. The correlation be- 
tween the 27-day variations in cosmic-ray 
intensity at these three stations is high, again 
indicating the world-wide character of the 
27-day variation in cosmic-ray intensity and 
its association with the 27-day variation in 
terrestrial magnetism. This additional ma- 
terial is now being subjected to statistical 
tests to determine whether, superposed on 
the quasi-persistent 27-day wave, a persistent 
27-day wave exists in the data from Chelten- 
ham and Christchurch. The existence of such 
a wave would, according to M. S. Vallarta 
and O. Godart {Review of Modern Physics, 
vol. 11, p. 180, 1939), indicate a permanent 
solar magnetic moment inclined to the Sun's 
axis of rotation. 

On causes for the variability of the 24-hour 
waves in cosmic-ray intensity. The varia- 
bility of the 24-hour wave in cosmic-ray 
intensity at Cheltenham derived from 155 
magnetically quiet days (international char- 
acter-figure C — 0.2) was compared with 



I2 4 



CARNEGIE INSTITUTION OF WASHINGTON 



that derived from 132 days with C — 1.4, 
and with that derived from 54 days with 
C — 1.7. The variability (square of two- 
dimensional standard deviation in the har- 
monic dial) for days with C— 1.7 was 
nearly twice as great as that for days with 
C — 0.2, whereas the variability for days with 
C— 1.4 was only about 12 per cent greater 
than that for days with C — 0.2. This indi- 
cates that the reliability of the average 24-hour 
wave from a given amount of available data 
cannot be materially improved by excluding 
days for which C — 1.7. Thus in determin- 
ing the sidereal diurnal variation the most 
reliable average would be obtained by includ- 
ing all the data — a result which could not 
have been anticipated without the above test. 

In addition, the variability of the 24-hour 
wave at Cheltenham was found to be nearly 
twice as great in winter as in summer, a 
result important to statistical tests for the 
reality of any sidereal wave in cosmic-ray 
intensity. 

On the cause for the diurnal variation in 
cosmic-ray intensity at Huancayo. According 
to the theory of M. S. Vallarta and O. Godart 
(see reference above), the diurnal variation 
of cosmic-ray intensity at Huancayo should 
be due practically entirely to the system of 
ionospheric currents responsible for the di- 
urnal variation in terrestrial magnetism. 
Since the latter at Huancayo is largely in the 
horizontal component, the Vallarta-Godart 
theory would require the diurnal variation in 
cosmic-ray intensity to be very similar to that 
in the horizontal magnetic component. How- 
ever, the average diurnal-variation curve for 
cosmic-ray intensity at Huancayo, derived 
from complete records on 1330 days, differs 
significantly from that for the horizontal 
magnetic component and thus does not sub- 
stantiate the Vallarta-Godart theory for the 
observed cosmic-ray diurnal variation at 
Huancayo. 

Sidereal diurnal variation in cosmic-ray 
intensity. For three complete years at Chel- 
tenham and four complete years at Huancayo 
the analysis of cosmic-ray data for the 24-hour 
and 12-hour sidereal waves in cosmic-ray 
intensity is now nearly completed. 



Bibliography 

Forbush, S. E. On the 27-day recurrence-ten- 
dency in cosmic-ray intensity at Huancayo, 
Peru. (Abstract) Trans. Amer. Geophys. 
Union, 20th annual meeting, pt. Ill, p. 368 

(i939)- 

World-wide changes in cosmic-ray in- 
tensity. Rev. Modern Phys., vol. 11, pp. 168— 
172 (i939)- 

A theory of world-wide periodic varia- 
tions of the intensity of cosmic radiation, by 
M. S. Vallarta and O. Godart (discussion). 
Rev. Modern Phys., vol. 11, p. 190 (1939). 

Cosmic radiation and terrestrial mag- 
netism. Cinquieme Rapport, Comm. Rela- 
tions Solaires et Terrestres (Firenze), pp. 
171-175 (1939). 

On the 27-day and 13.5-day waves in 



cosmic-ray intensity and their relation to 
corresponding waves in terrestrial-magnetic 
activity. Trans. Washington meeting, Sept. 
1939; Internat. Union Geod. and Geophys., 
Assoc. Terr. Mag. and Elec, Bull. No. 11, 
pp. 438-452 (1940). 

Report on Cosmic-Ray Problems 

V. F. Hess 
Fordham University, New Yor\, New Yor\ 

Work has been done on the following two 
problems with the aid of the grant from the 
Carnegie Institution of Washington. 

Cosmic-ray measurements on board ship 
from New Yor\ to Valparaiso, with model-C 
meter. Arrangements with the Grace Line, 
Inc., of New York have been made concern- 
ing the installation of one of the Committee's 
large model-C meters on board the freighter 
Santa Ana. This instrument will be placed 
in a deckhouse erected amidships. The de- 
mountable deckhouse used within the last two 
years on board the steamship Northland on 
trips from Vancouver to Juneau (Alaska) by 
Professor Loughridge was shipped from 
Seattle via Panama to New York, where it 
arrived on June 29, 1940. 

The cosmic-ray meter was sent from Seattle 
to Chicago in June. Professor Compton sug- 
gested that the overhauling of this instrument 
be done in his laboratory under his super- 
vision. Therefore the writer and two collabo- 
rators, Fr. Berry, S. J., Associate Professor of 
Physics (Fordham University), and F. Bene- 



SPECIAL PROJECTS: TERRESTRIAL SCIENCES 



I2 5 



detto, worked for several weeks in Chicago, 
acquainting themselves with the instrument 
and doing some of the most urgent necessary 
repairs. The first trip to Valparaiso is 
scheduled for September 1940. 

Meson-disintegration and air-mass effects at 
sea-level. Professor Swann kindly authorized 
construction of an elaborate twin-counter tele- 
scope for the writer's measurements in the 
shop of the Bartol Research Foundation. This 
telescope will allow for continuous independ- 
ent registration of mesons coming from the 
vertical by two sets of counter-trays with well- 
defined sensitive areas. The design was com- 
pleted in May 1940; the telescope is under 
construction with the aid of a special grant 
from the American Philosophical Society. 

Studies of Cosmic Rays 

Thomas H. Johnson 

Bartol Research Foundation of the Franklin 

Institute, Swarthmore, Pennsylvania 

The studies made during the past year 
under grants from the Carnegie Institution 
have had the following basic objectives: (1) 
to obtain further evidence of the nature of 
the primary cosmic radiation before its en- 
counter with the Earth's atmosphere; (2) to 
investigate the processes of interaction of the 
penetrating cosmic rays, or mesons, with 
matter and to study the duration and the 
factors affecting the lifetime of a meson before 
its final spontaneous disintegration into an 
electron; and (3) to obtain further evidence 
of the production of mesons by protons. 
With these objectives in mind the following 
experimental investigations have been carried 
out. 

Balloon-flights to study the importance of 
showers of simultaneous cosmic rays as a 
disturbing element in the measurement of 
cosmic rays from definite directions in the 
stratosphere. These studies have been made 
with the particular purpose of clarifying the 
interpretation of results reported last year 
(Year Book No. 38, p. 341) of balloon-flight 
measurements of the east-west asymmetry of 
the soft component cosmic rays in the strato- 
sphere. Those measurements showed that, 



unlike the hard component rays at sea-level, 
the soft component exhibited no east-west 
asymmetry, and it was concluded that the 
two components arise from different types of 
primary particle, the soft component from 
electrons, equally positive and negative, and 
the hard component from a predominantly 
positive proton component of the primary 
radiation. This interpretation was based upon 
the assumption that the counts recorded by 
a triple-coincidence cosmic-ray counter are 
produced by single cosmic rays passing in 
the direction of the counter-train, and that 
no appreciable part of those counts is due to 
showers of three or more simultaneous rays 
having directions other than that determined 
by the counter-train. In order to test the 
validity of this assumption, flights were made 
into the stratosphere from Swarthmore with 
instruments containing three coincidence- 
counters which were alternated between two 
positions, an in-line position and an out-of- 
line position. In the stratosphere the out- 
of-line counts measuring the effect of the 
showers never exceeded 5 per cent of the 
in-line counts, and it was shown that by far 
the greater part of the in-line counting-rate 
was produced, as originally assumed, by 
single cosmic rays having the direction of 
the counter-train. Hence the important con- 
clusions drawn from the asymmetry studies 
in Panama stand unchallenged. 

Coincidence counter-measurements of the 
proper life of the meson. Continuing the 
experiments outlined in last year's report, the 
intensities of mesons under equivalent ab- 
sorbing layers of air and of other dense sub- 
stances have been compared in order to esti- 
mate the importance of the time-of-flight 
factor and its effect upon the intensities. This 
has been done both for the total meson- 
intensity and for that part of it lying within 
a narrow range of low energies. In all energy- 
ranges the proper life of the meson has been 
found to be of the order of 2 to 3 micro- 
seconds and, within the accuracy of the ex- 
periments, to be independent of the energy. 
Some of the evidence, however, indicates that 
slow mesons are possibly being removed from 



126 



CARNEGIE INSTITUTION OF WASHINGTON 



the beam by processes other than that of 
disintegration before they have been com- 
pletely absorbed by ionization. Further tests 
of this possibility are being made in an experi- 
ment for comparing the absorption of low- 
energy mesons in carbon and in lead. An 
extensive set of data has already been ob- 
tained, but the final conclusions from these 
studies must await further analysis. 

Studies with a large Wilson cloud-chamber. 
With funds provided jointly by the Carnegie 
Institution of Washington and the Bartol 
Research Foundation, a large Wilson cloud- 
chamber has been constructed and put into 
operation. This chamber is 23 inches in 
diameter and 6 inches deep. Up to the time 
of writing, 8000 stereoscopic photographs 
have been obtained showing mesons travers- 
ing three lead plates placed in the chamber 
whose thicknesses total 7 centimeters. The 
analysis of these photographs, and of others 
to be taken, is under way and has the follow- 
ing objectives: (1) to determine to what 
extent mesons occur in groups of two or 
more simultaneous rays resulting from pro- 
duction-processes taking place in material 
above or in the chamber; (2) to observe stop- 
ping and scattering of mesons in material in 
order to obtain a more accurate picture than 
that now available of the relative importance 
of these processes in their effect upon the 
quantity usually defined as the absorption- 
coefficient; (3) to observe the effect of mesons 
in producing nuclear transformations and 
artificial radioactivity; (4) to seek further 
evidence for the existence of protons in the 
cosmic radiation, for the production of mesons 
by protons, and for the inverse reaction, the 
production of protons by mesons. Some re- 
sults in these far reaching studies have already 
been obtained. We have shown that the 
number of associated mesons, item (1), is 
considerably less than that indicated by the 
experiments of Braddick and Hensby (Na- 
ture, vol. 144, p. 1012, 1939). We have also 
found definite evidence for the existence of 
high-energy protons in the penetrating com- 
ponent of the cosmic radiation at sea-level. 
These experiments have pointed the way to 



an experiment now being planned, for which 
funds have been provided by the Carnegie 
Institution of Washington, for the measure- 
ment of the proton-component of the cosmic 
radiation in the stratosphere. 

The east-west asymmetry of the cosmic 
radiation in high latitudes and the balance of 
charge between the positive and negative rays 
occurring in the atmosphere. Cooperating in 
our program, Fred Seidl has made an exten- 
sive set of measurements of the east-west 
asymmetry at Troy, New York, in a latitude 
well above the knee of the latitude-effect 
where no primary asymmetry can be expected. 
An asymmetry of the order of 1 per cent is 
found at that station and can be used in 
calculating the excess of positive cosmic rays 
in the atmosphere. Results in accord with 
those reported by Hughes {Physical Review, 
vol. 57, p. 592, 1940) from measurements 
made with a large magnetic cloud-chamber 
have been obtained. 

Technical developments. New devices de- 
veloped in connection with our work with 
the cloud-chamber include a new type of 
mercury capillary arc, a new type of circuit 
for the control and operation of the arc, a 
flash-photometer for measuring the photo- 
graphic exposure resulting from a flash, and 
a stereoscopic projector for viewing and 
measuring tracks photographed in the cloud- 
chamber. Certain novel features in the design 
and construction of the Wilson cloud- 
chamber have also been developed. 

Personnel. This program has been carried 
on with the full-time cooperation of Dr. 
J. Griffiths Barry, M. A. Pomerantz, and 
Ralph P. Shutt. Acknowledgment is also 
made of the cooperation of Fred G. P. Seidl. 

Bibliography 

Barry, J. G., and T. H. Johnson. The contribu- 
tion of showers to the coincidences recorded 
at high elevations. (Abstract) Phys. Rev., 
vol. 57, p. 555 (1940). 

Johnson, T. H. New evidence regarding the 
nature of the primary cosmic radiation. (Ab- 
stract) Trans. Amer. Geophys. Union, 20th 
annual meeting, pt. Ill, p. 367 (1939). 

The intensity of the primary cosmic ra- 
diation and its energy-distribution. Jour. 
Franklin Inst., vol. 228, pp. 104-108 (1939). 



SPECIAL PROJECTS: TERRESTRIAL SCIENCES 



127 



Johnson, T. H. A note on the nature of the 
primary cosmic radiation. Jour. Franklin 
Inst., vol. 228, pp. 792-796 (1939). 

The angular dispersion of the cosmic 

radiation in the upper atmosphere resulting 
from deflections of low-energy particles in 
the Earth's magnetic field. Phys. Rev., vol. 
56, pp. 226-231 (1939); (abstract) Phys. 
Rev., vol. 56, p. 210 (1939); (abstract) Jour. 
Franklin Inst., vol. 229, pp. 387-388 (1940). 

Evidence that protons are the primary 

particles of the hard component. Rev. Mod- 
ern Phys., vol. 11, pp. 208-210 (1939); (ab- 
stract) Jour. Franklin Inst., vol. 229, pp. 668— 
670 (1940). 

Recent advances in the investigation of 

cosmic rays. (Abstract) Jour. Franklin Inst., 
vol. 229, pp. 256-257 (1940). 

The angular dispersion of the cosmic 

radiation in the upper atmosphere resulting 
from deflections of low-energy particles in 
the Earth's magnetic field. Jour. Franklin 
Inst., vol. 229, pp. 387-388 (1940). 

and J. G. Barry. The east-west symmetry 

of the cosmic radiation at very high eleva- 
tions near the equator and evidence that 
protons constitute the primary particles of 
the hard component. Phys. Rev., vol. 56, 
pp. 219-226 (1939); (abstract) Jour. Frank- 
lin Inst., vol. 229, pp. 386-387 (1940). 

The east-west asymmetry of the 

cosmic radiation at very high elevations near 
the equator. Jour. Franklin Inst., vol. 229, 
pp. 115-117 (1940). 

The contributions of showers to 

the coincidences recorded at high elevations. 
Phys. Rev., vol. 57, pp. 245-246 (1940); 
Jour. Franklin Inst., vol. 229, pp. 799—802 
(1940). 

and R. P. Shutt. Direct evidence 



of a proton component of the cosmic radia- 
tion. Phys. Rev., vol. 57, pp. 1047-1048 
(1940). 

— and S. A. Korff. An improved radio- 
barograph. (Abstract) Jour. Franklin Inst., 
vol. 229, p. 252 (1940). 

Geiger-counter measurements in 

the upper atmosphere bearing upon the 
nature of the radiation from solar flares and 
radio fade-outs. (Abstract) Jour. Franklin 
Inst., vol. 229, pp. 252-253 (1940). 

— and M. A. Pomerantz. The difference in 
the absorption of cosmic rays in air and 
water and the instability of the barytron. 
Jour. Franklin Inst., vol. 229, pp. 112-115 
(1940). 

— R. P. Shutt, and J. G. Barry. On the 
occurrence of associated mesons. (Abstract) 
Phys. Rev., vol. 57, p. 1062 (1940). 



Pomerantz, M. A., and T. H. Johnson. The 
relative meson stopping power of lead and 
water. (Abstract) Phys. Rev., vol. 57, p. 555 
(1940). 

Cosmic-Ray Investigations 

S. A. Korff 

Bartol Research Foundation of the Franklin 

Institute, Swarthmore , Pennsylvania 

The following studies were carried on be- 
tween July 1, 1939 and June 30, 1940, in the 
field of cosmic rays, with the aid of funds 
made available through the Carnegie Insti- 
tution of Washington. 

Cooperation with United States Antarctic 
Service. At the invitation of the U. S. Ant- 
arctic Service, a program of cosmic-ray 
observations to be made on the first U. S. 
Antarctic Expedition was prepared. This 
program was as follows: 

a) Latitude-effect observations: Two cos- 
mic-ray meters were operated on board U.S.S. 
North Star on its journey as supply-ship of 
the Expedition. One was a Millikan-type 
electroscope made available by the Carnegie 
Institution of Washington, and the other a 
Geiger counter-apparatus built at the Bartol 
Foundation. The electroscope was operated 
between Philadelphia and Little America, and 
the counter-apparatus remained on board the 
ship during its return voyage. 

b) Variation of cosmic-ray intensity with 
elevation: One of the two Millikan-type 
meters has been carried to elevations of 21,000 
feet in airplane flights at Little America. It 
is planned to continue the flight program. 

c) Long-period installation: Two of the 
Millikan-type meters made available by the 
Carnegie Institution were installed in Little 
America for operation over the current year 
there. The records from these, when returned 
to the United States, will be analyzed for 
fluctuations correlating with magnetic storms, 
auroras, and external temperature. 

The following results have been obtained 
to date: The latitude-effect, measured by 
both the counter and the electroscope, showed 
the familiar "knee" in the cosmic-ray intensity 
at geomagnetic latitude 38 ° south. South of 



128 



CARNEGIE INSTITUTION OF WASHINGTON 



this point the cosmic-ray intensity continued 
to rise, as far as Little America (77° south geo- 
magnetic), the southernmost point reached. 
The entire amount of this rise was found to 
be attributable to the decreasing external 
temperature, and hence to the lowering of 
that level in the atmosphere at which the 
penetrating component of the cosmic rays, 
namely, the mesons, is generated. It will 
be recalled that, in the southern hemisphere, 
no adequate observations have hitherto been 
made south of 45 °. 

It was found that a single Geiger counter, 
enclosed in a lead shield and using a suitable 
scaling and recording circuit, could be used 
as a reliable instrument for measuring the 
total cosmic-ray intensity. Since the counter 
counts the number of cosmic-ray particles, 
while the electroscope measures the ioniza- 
tion which the particles produce, a correlation 
of the two instruments provides new infor- 
mation regarding the average amount of 
ionization produced by each ray. The details 
of this are at present being studied. A pre- 
liminary calculation indicates that the ratio of 
electrons to mesons at sea-level does not vary 
with latitude south of 40 . This, taken in 
conjunction with the variation with external 
temperature, suggests that all the cosmic-ray 
electrons at sea-level are secondaries produced 
by the mesons. 

Radio balloon-observations . (a) Generation 
of soft rays, and influence of surrounding 
matter on measurements in the stratosphere: 
On August 9, 1939, a flight was made in 
which a single Geiger counter was caused to 
occupy four positions with respect to lead 
blocks. The position of the counter was con- 
trolled by a small electric motor, and the 
complete cycle of positions was repeated every 
5 minutes. This flight represents the first 
control-experiment made in the upper atmos- 
phere in which the behavior of one instru- 
ment under four different conditions could 
be recorded. 

It was found that the counting rate was 
increased when the counter was surrounded 
by lead blocks, as compared with the rate 
when lead was distant. The counting rate 



was also increased, although not so much, 
when a lead block was placed above the 
counter. This was attributed to the gener- 
ation of showers of secondaries by the cascade- 
processes produced by the cosmic radiation 
in the top lead block. The counting rate was 
also found to increase when lead was placed 
below the counter. This was due to the up- 
ward reflection, from the lower lead block, 
of rays incident on the block from above. 
Since high-energy rays tend to perpetuate 
their downward direction, the relatively large 
increase in the counting rate with the lead 
below the counter indicated that there was 
a very abundant radiation of low energy in 
the upper atmosphere. This radiation pre- 
sumably consists of both charged particles 
and photons. 

b) Flights with neutron-counters: The 
program of balloon-flights using counters 
capable of detecting slow neutrons, and other 
counters capable of detecting fast neutrons, 
was continued. Measurements of slow and 
fast neutrons in the upper atmosphere have 
been made, and the number of neutrons as 
a function of elevation was determined. 

It will be recalled that boron-trifluoride 
counters, of the type described in last year's 
report, measure both slow and fast neutrons. 
The slow neutrons are found by counting 
the number of alpha particles which they 
produce by disintegrating the boron. The 
fast neutrons are detected by counting the 
number of recoil-nuclei which they produce 
as they pass through the chamber. Counters 
filled with gases which do not yield alpha 
particles through slow-neutron-induced dis- 
integrations will count the fast neutrons 
only. Furthermore, the variation of the count- 
ing rate with the applied counter voltage 
makes possible a determination of the energy 
of the neutron which produces the recoil. 
Such a control-flight was made, the voltage 
on the counter being varied in a predeter- 
mined manner during the flight. Hence these 
studies reveal the ratio of fast to slow neu- 
trons, as well as allowing measurements to 
be made of the energies of the fast neutrons. 
This series of flights is still in progress. 



SPECIAL PROJECTS: TERRESTRIAL SCIENCES 



129 



The preliminary result is that fast neutrons 
are quite abundant in the upper atmosphere; 
that of the fast neutrons, many lie in the 
energy-range between two and ten million 
volts or more; and that not all the fast neu- 
trons are slowed down through collision- 
processes, some being captured at high ener- 
gies. It was found that the neutrons were 
numerous, and indeed were about as abun- 
dant numerically as the charged particles in 
the cosmic radiation. Because the average 
neutron-energy is below ten million volts, 
however, as compared with the average 
energy of 20 or more times that amount 
exhibited by the charged cosmic-ray particles, 
the neutrons do not produce a large fraction 
of the cosmic-ray ionization. 

c) Studies of proportional counters: The 
task of developing and studying the proper- 
ties of proportional counters has been con- 
tinued. It was found that the discharge of 
a counter can be made proportional to the 
amount of ionization occurring in the counter 
if it is operated in the proper voltage-range 
and if the gain of the amplifier detecting the 
pulses is properly adjusted. With care, the 
proportional counter can be made to be an 
accurate instrument with a wide variety of 
uses. In this work, it was developed for the 
purpose of studying the amount of ionization 
produced by various particles in the cosmic 
radiation. 

d) Production of neutrons by cosmic radi- 
ation: The process by which the cosmic 
radiation produces neutrons has been investi- 
gated. Because of the theoretical instability 
and finite lifetime of neutrons, it seems highly 
probable that none of the neutrons observed 
in the upper atmosphere are primary particles, 
but rather that they have been produced by 
the high-energy cosmic radiation impinging 
on the upper atmosphere. The process by 
which this occurs is a new and important 
one in the domain of ultra-high-energy 
physics. A year ago it was suggested that this 
process was probably one in which the high- 
energy photons associated with the cosmic 
radiation caused neutrons to be evaporated 
out of the nuclei of nitrogen and oxygen of 

12 



the atmosphere. Further evidence for this is 
now at hand. 

Since the high-energy photons are con- 
nected with, and themselves produce, large 
cascade-showers, it should follow that neu- 
trons and large showers should be associated. 
An experiment was designed to test this by 
counting coincidences between the discharges 
of a neutron-counter and a shower-counter. 
Coincidences were observed, and were found 
to occur at a rate which enabled an inde- 
pendent calculation of the rate of production 
of neutrons to be made. On the average, 
one neutron is produced in every hundred 
showers. 

The consequences of neutron-production 
and the life-history of the neutrons in the 
atmosphere have been investigated from the 
point of view of nuclear theory. It was shown 
that neutrons will be produced with energies 
of the order of ten to thirty million electron- 
volts. They will then lose energy, first by 
inelastic and then by elastic collisions, until 
when slow they are finally absorbed by 
nitrogen nuclei in the atmosphere. 

e) Comparison of radioactive neutron- 
sources: In the course of the investigation of 
intensities of neutrons, it was found necessary 
to standardize neutron-counters and neutron- 
sources. A study was made of the compara- 
tive neutron-producing efficiencies of a num- 
ber of radium-beryllium neutron-sources. It 
was found that each source had a different 
efficiency, and that radium-beryllium sources 
are more efficient than radon-beryllium 
sources. The gamma-ray intensity cannot be 
taken as indicating the expected neutron- 
intensity; the latter also depends on the 
amount of beryllium, the manner of mixing, 
and the amount of compression of the mix- 
ture. A procedure was developed by which 
rapid evaluations of efficiencies in terms of 
a given source as a standard could be made. 

Acknowledgments. The author wishes to 
acknowledge many helpful discussions with 
his colleagues at the Bartol Research Founda- 
tion. Thanks are also due the Burgess Bat- 
tery Company and the Eastman Kodak 
Company for gifts of apparatus for the 
Antarctic cosmic-ray studies. 



130 



CARNEGIE INSTITUTION OF WASHINGTON 



Bibliography 

Bethe, H. A., S. A. Korff, and G. Placzek. On 
the interpretation of neutron measurements 
in cosmic radiation. Phys. Rev., vol. 57, 
PP- 573-587 (i94o)- 

Johnson, T. H., and S. A. Korff. An improved 
radiobarograph. (Abstract) Jour. Franklin 
Inst., vol. 229, p. 252 (1940). 

Geiger-counter measurements in 

the upper atmosphere bearing upon the na- 
ture of the radiation from solar flares and 
radio fade-outs. (Abstract) Jour. Franklin 
Inst., vol. 229, pp. 252-253 (1940). 

Korff, S. A. Evidence for neutrons in the cosmic 
radiation. (Abstract) Phys. Rev., vol. 56, 
p. 210 (1939). 

Recent studies at high elevations. Rev. 

Modern Phys., vol. 11, pp. 211-219 (1939); 
(abstract) Jour. Franklin Inst., vol. 229, pp. 
664-665 (1940). 

Fast neutron measurements with recoil 

counters. Phys. Rev., vol. 56, pp. 1241-1242 
(1939); Jour. Franklin Inst., vol. 229, pp. 
802-804 (1940). 

The production of neutrons by cosmic- 
ray showers. (Abstract) Phys. Rev., vol. 57, 
p. 555 (1940). 

Solar influences on the cosmic-ray inten- 
sity at high elevations. Jour. Franklin Inst., 
vol. 229, pp. 21-27 ( I 94°); (abstract) Trans. 
Amer. Geophys. Union, 20th annual meet- 
ing, pt. Ill, pp. 367-368 (1939). 

On the contribution to the ionization at 

sea-level produced by the neutrons in the 
cosmic radiation. Terr. Mag., vol. 45, pp. 

133-134 (i94o)- 

and E. T. Clarke. The upward radiation 

produced by cosmic rays at high altitudes. 
Phys. Rev., vol. 56, p. 704 (1939); Jour. 
Franklin Inst., vol. 229, pp. 525-527 (1940). 

and W. E. Danforth. Correlation of 

counter and electroscope measurements of 
cosmic radiation in the stratosphere. Jour. 
Franklin Inst., vol. 228, pp. 159-167 (1939). 

Neutron measurements with 



boron-trifluoride counters. Jour. Franklin 
Inst., vol. 229, pp. 253-255 (1940). 

Studies of Cosmic Rays 

Robert A. Milli\an 

California Institute of Technology, 

Pasadena, California 

The major researches which have been pur- 
sued and the results obtained between July 1, 
1939 and June 30, 1940, in the cosmic-ray 
studies carried on at the California Institute 



of Technology with the aid of funds supplied 
by the Carnegie Corporation of New York 
administered by the Carnegie Institution of 
Washington, may be very briefly summarized 
as follows: (1) the measurement through 
45 balloon-flights in India, extending nearly 
to the top of the atmosphere, of the latitude- 
effect in the equatorial belt on the total in- 
coming cosmic-ray energy and its east-west 
distribution; (2) the building of a large 
cosmic-ray cloud-chamber of high resolving 
power in the endeavor to obtain more ac- 
curate data than are now available on the 
mass and nature of the mesotron; (3) the rep- 
etition, with the aid of the most modern and 
improved techniques, of the original Millikan- 
Cameron measurements of the ratio of the 
absorption-coefficients for cosmic rays of air 
and water with a view to the computation 
from these data of the lifetime of the meso- 
tron; (4) the completion of the sea-level meas- 
urements between Seattle and the Strait of 
Magellan of the seasonal, or "atmospheric 
temperature," effect on the sea-level intensity 
of cosmic rays, an effect now interpreted in 
terms of the lifetime of the mesotron. 

Milli\an, Neher, and Pickering's measure- 
ments in India. These measurements were 
made in collaboration with the British-Indian 
Meteorological Service in the three different 
latitudes of Bangalore (magnetic latitude 3 
north), Agra (magnetic latitude 17^3 north), 
and Peshawar (magnetic latitude 25 ° north). 
In the various flights four different types of 
recording techniques were used, as follows: 
( 1 ) Neher photographically recording electro- 
scopes. These had to be recovered by the 
populace and sent back to us. They yielded 
the cosmic-ray energy coming in from all 
directions at all altitudes. (2) Neher-Picker- 
ing single-tube counters arranged to transmit 
back by radio to the home station the records 
of temperatures, pressures, and cosmic-ray 
shots passing the single counter-tube at all 
altitudes, and therefore yielding counts on 
all the shots from all directions passing 
through a given volume. The curves are 
similar to those yielded by (1) and served 
as a check upon the latter, but with certain 
significant differences due to the fact that 



SPECIAL PROJECTS: TERRESTRIAL SCIENCES 



131 



coincident shots are not registered by counters 
but are registered by electroscopes. (3) Neher- 
Pickering double counter-tubes arranged to 
register all the shots passing through the tubes 
vertically at all altitudes. (4) Johnson-Neher- 
Pickering techniques for measuring east-west 
effects up to very high altitudes. The re- 
turned instruments from these flights have 
not yet (July 6) all been received by us from 
the British-Indian Meteorological Office, so 
that the final results cannot now be reported. 
The preliminary results, however, seem to 
be favorable to the theory of the origin of the 
cosmic rays which led to these experiments. 

Anderson and Neddermeyer cloud-chamber 
wor\. Most of the difficulties which appeared 
to confront the building of a huge magnet 
and cloud-chamber suitable for improving the 
resolving power of mesotron-measuring in- 
struments have been overcome and there is 
now good promise of early results of signifi- 
cance. The job has been a long and difficult 
one and it is not yet finished. 

Neher and Stever's measurements on the 
ratio of the absorbing power of air and water. 
In the original 1925 Millikan-Cameron meas- 
urements in high-altitude, snow-fed lakes, 
the difference in the altitudes of the two lakes 
chosen, namely, Muir Lake (altitude 11,900 
feet) and Arrowhead Lake (altitude 5100 
feet), was but 6800 feet. Nevertheless, there 
were definite, though small, indications of a 
higher absorption of cosmic rays by air than 
by water of the same mass, that is, an indi- 
cation of the breakdown of the mass-absorp- 
tion law. However, these were taken by 
Millikan and Cameron as falling within the 
limits of the experimental uncertainties in- 
hering not only in the crudity of the electro- 
scopes available at that time, but also in the 
smallness of the difference in altitude of the 
two lakes and particularly in the possible 
shielding effects of Mount Whitney upon 
Muir Lake situated just under its brow. 

Accordingly, in the summer of 1939 Neher 
and Stever chose two lakes, one in the high 
Sierras and one near sea-level, of 12,000 feet 
difference in altitude, both unshielded by 
surrounding mountains; and, using the best 
of modern sensitive Neher electroscopes, they 



obtained a ratio of 1.15 for the apparent ab- 
sorptions of air and water. Interpreting this 
difference on the basis of the modern theory 
of the radioactive decay of the mesotron, they 
obtain for the mean rest lifetime of the meso- 
tron 2.7X10" 6 second. These results fix this 
value with a good deal of precision. 

Millikan and Neher 's measurements on the 
sea-level "atmospheric-temperature" effect on 
cosmic rays. In three round trips from 
Seattle to the Strait of Magellan, Millikan 
and Neher find between Los Angeles and the 
Strait, when all readings are reduced to a 
standard barometer, no seasonal or temper- 
ature-effect at all that is outside the limits of 
the daily, or even the semiweekly, fluctu- 
ations. But this was not the case between 
Los Angeles and Seattle. At the Seattle lati- 
tude the winter and spring readings were as 
much as 2 per cent higher than the summer 
and fall readings, this change at Seattle oc- 
curring while the intensity at Los Angeles 
was remaining essentially constant. 

They interpret this effect, as Blackett had 
done before them in the case of the like meas- 
urements of Hess and Compton, in terms 
of the contraction in the thickness of the 
atmosphere in the northern latitudes in winter 
and the resulting increase in the effective air- 
path of the mesotron during its lifetime and 
hence of the ionization produced by it during 
its life. 

Bibliography 

Boggild, J. K., I. C. Kuo, S. H. Neddermeyer, 
and C. D. Anderson. Collision energy loss 
of low-energy cosmic-ray electrons. Phys. 
Rev., vol. 57, pp. 356-357 (1940). 

Millikan, R. A., and H. V. Neher. New 
evidence for a change with time of the 
total energy brought into the Earth by 
cosmic rays. Phys. Rev., vol. 56, pp. 491- 
493 (i939)- 

and D. O. Smith. Seasonal 

cosmic-ray effects at sea level. Phys. Rev., 
vol. 56, pp. 487-490 (1939). 

Neddermeyer, Seth H., and Carl D. Anderson. 
Nature of cosmic-ray particles. Rev. Modern 
Phys., vol. 11, pp. 191-207 (1939). 

Vargus, J. A., Jr. The angular distribution of 
cosmic-ray particles scattered in one centi- 
meter of platinum. Phys. Rev., vol. 56, pp. 
480-481 (1939). 



132 



CARNEGIE INSTITUTION OF WASHINGTON 



Zwicky, F. Production of atomic rays and of 
cosmic rays in supernovae. Proc. Nat. Acad. 
Sci., vol. 25, pp. 338-344 (1939). 

Motion of Cosmic-Ray Particles in the 
Geomagnetic Field 

M. S. Vallarta 

Massachusetts Institute of Technology, 

Cam bridge, Massac h usetts 

The problem undertaken concerns the mo- 
tion of cosmic-ray particles in the magnetic 
field of the Earth, the theory of magnetic 
storms, and related matters. The major por- 
tion of the work will be done using the 
differential analyzer. Because there have been 
delays in making available the new differ- 
ential analyzer at the Massachusetts Institute 
of Technology, it has been possible so far 
only to take the necessary preliminary steps. 



These preliminary calculations have been 
made during March to July 1940 by Dr. R. A. 
Hutner, Research Assistant at the Massachu- 
setts Institute of Technology (paid from 
funds allotted by the Carnegie Institution of 
Washington). We are now ready to pro- 
ceed with the analysis of the penumbra of 
cosmic radiation and the consequent deter- 
mination of the energy-spectrum of primary 
rays, as well as with the theory of the galactic- 
rotation effect and that of magnetic storms, 
as soon as the new machine is made available. 

Bibliography 

Vallarta, M. S. The determination of the energy 
spectrum of primary cosmic rays. Rev. 
Modern Phys., vol. 11, pp. 239-240 (1939). 

and O. Godart. A theory of world-wide 

periodic variations of the intensity of cos- 
mic radiation. Rev. Modern Phys., vol. n, 
pp. 180-190 (1939). 



Committee on Study of the Surface Features of the Moon. Progress report for the period 
July 1939 to ]une 1940. (For previous reports see Year Books Nos. 26-38.) 



A report on the results of visual measure- 
ments of the percentage polarization in beams 
of light from different parts of the moon's 
surface and in sunlight scattered by terrestrial 
materials at various phase angles is in prepa- 
ration. Plans had been made to complete this 
report during the past winter, but other un- 
expected tasks interfered with the work. 

Progress has been made in the topographic 
mapping of the important surface features of 
the moon by measurement of their slope 
angles and dimensions as recorded on the 
series of moon photographs taken in 1938 
with the 100-inch telescope. This task is time- 
consuming and slow, but topographic maps 
are gradually being produced of many of the 
craters and mountains on the moon, and these 
will be useful later in connection with de- 
tailed physiographic studies of the moon's 
surface. An experimental viewing stereo- 
scope has been built which is well suited to 
the study of lunar features with the aid of 
stereoscopic pairs of prints, and valuable in- 
formation on their mutual relations has been 
obtained. The stereoscope permits use of a 
wide base and is equipped with a series of 



lenses that enable the observer to use different 
degrees of magnification and to recognize 
relations between features that are not dis- 
cernible on a single print or negative. The 
stereoscope is not equipped for photogram- 
metric measurements for the reason that the 
surface of reference is not a plane but an 
approximately spherical surface. The compli- 
cations arising from this fact are so serious 
that, with the limited number of good stereo- 
scopic pairs of photographs now available, 
construction of an instrument suitable for the 
measurements would not be justified. 

Work on developing and testing the two 
photoelectric cell methods for measuring the 
percentage polarization in light scattered in 
different directions by lunar and terrestrial 
materials has been continued; a serious diffi- 
culty in this problem is the change in re- 
sponse of the photoelectric cell with change 
in azimuth of the plane of vibration of the 
incident light. This change in behavior of 
the photoelectric cell occurs when the direc- 
tion of the incident plane-polarized beam of 
light is not perpendicular to the sensitive sur- 
face of the photoelectric cell. If, as is usually 



SPECIAL PROJECTS: TERRESTRIAL SCIENCES 



133 



the case, the surface of the cell is curved, it 
is difficult to avoid oblique incidence for part 
of the incoming beam which covers an appre- 
ciable area on the sensitive surface of the cell. 
One remedy is to make a special photoelectric 
cell with a flat window and a plane area of 
the sensitive surface opposite the window. 
Only this portion of the sensitive surface is 
to be used for the receiving surface, and on 
it the incident light will impinge normally. 
An alternative procedure is to depolarize the 
light before it reaches the photoelectric cell; 
this requires the use of a properly oriented, 
plane-parallel plate of glass or other trans- 
parent material that can be tilted at various 
angles to the line of propagation of the trans- 
mitted beam; the tilted plate introduces an 
amount of polarization into the transmitted 
beam just sufficient to compensate the polar- 
ization in the beam itself and thus to produce 
light that is nonpolarized. From the angle 
of tilt of the plate necessary to compensate 
the polarization in the beam it is possible to 
compute the percentage amount of polariza- 
tion in the beam itself. 

Final measurements of polarization by the 
photoelectric cell methods requiring the use 
of a direct-current amplifier or of an alternat- 
ing-current amplifier must await tests with 
the special photoelectric cell and further im- 
provement in the amplifying systems. 

During the lunar eclipse of October 27, 
1939 Dr. Edison Pettit, of Mount Wilson 
Observatory, measured the radiations from 
the moon with the aid of a vacuum thermo- 
couple attached to the 20-inch reflecting tele- 
scope of 40 inches focal length and aperture 
ratio F/2. In these measurements lunar sur- 
face temperatures were determined by obser- 
vations of galvanometer deflections produced 
by the thermocouple receiving the lunar radi- 
ations, either direct, or through a microscope 
cover glass 0.16 mm thick, or through a water 
cell 1 cm thick with quartz windows. For 
a small area near the center of the disk (0.85 
radius from the north limb) Dr. Pettit found 
that the temperature fell from 371 ° K to 



200 K ( + 98 Cto —73 C) during the first 
partial phase and dropped slowly to 175 K 
(—98° C) during totality. At the beginning 
of totality the temperature fell at the rate 
of 30 C per hour; at the end of the first hour 
the rate was 7 C per hour. The rate of radi- 
ation during the partial phases was nearly 
proportional to the energy received, except 
for low temperatures. 

On June 14, 1927 Drs. Pettit and Nichol- 
son made 17 sets of measurements of the 
radiations from the moon during its eclipse. 
The 100-inch telescope was used and galva- 
nometer deflections were obtained with cover 
glass, with water cell, and without absorbing 
screen (free deflections). At the start the free 
deflection was 617 mm; at the end of totality 
it was 1.48 mm; the sensitivity of the appa- 
ratus was varied by changing the electrical 
circuit of the thermocouple. The measure- 
ments were made on a small area near the 
edge of the moon's disk (0.05 lunar radius 
from the south limb). The values of lunar 
temperatures obtained do not differ greatly 
from those found in 1939 by Dr. Pettit, who 
adopted certain improvements in procedure 
by which 39 sets of readings were made and 
the sensitivity during the total phase was in- 
creased so that the deflection at the end of 
totality was 54 mm, as against 1.48 mm in 
the 1927 arrangement. In his report upon 
the 1939 results Dr. Pettit suggests several 
other improvements in procedure for meas- 
urement of the radiations during a lunar 
eclipse. It is hoped that these may be tested 
during a future eclipse and additional data 
secured on lunar surface temperatures and 
on the thermal characteristics of the materials 
exposed at its surface. 

W. S. Adams 

J. P. Buwalda 

A. L. Day 

P. S. Epstein 

E. Pettit 

H. N. Russell 

F. E. Wright, Chairman 



i34 



CARNEGIE INSTITUTION OF WASHINGTON 



California Institute of Technology, Pasadena, California. Cooperative researches at the 
Seismological Laboratory. (For previous reports see Year Books Nos. 37, 38.) 



The Seismological Laboratory at Pasadena 
has continued attack during the past year on 
problems relating to local or southern Cali- 
fornia earthquakes, to earthquakes in other 
parts of the world and their bearing on earth 
constitution and structure and connected geo- 
physical problems, and to the new design 
and continuous improvement of seismic appa- 
ratus both for recording the oscillations in 
earthquakes customarily studied heretofore 
and for securing records of other elements in 
earthquake motion to which less attention has 
been devoted in the past. 

The geographical distribution of earth- 
quakes over the earth has been studied by 
others at various times, but a more complete 
and quantitative investigation was under- 
taken by Dr. Gutenberg and Dr. Richter, and 
a paper embodying the results was prepared. 
An estimate was made of the frequencies of 
shocks of various magnitudes. Those of mag- 
nitude 8 occur on the earth at the rate of 
about 1 per year, those of magnitude 7 at 
the rate of about 10 per year, and the rate 
increases with smaller magnitudes, so that 
at least 100,000 of magnitude 3 are estimated 
to occur each year. This latter estimate de- 
pends largely on the frequency of local shocks 
in the southern California region. The results 
as a whole depend mainly on the data ac- 
cumulated at Pasadena and Huancayo. The 
purpose of the study was to determine what 
belts of the earth are most active seismically, 
what the relation of these seismic belts is to 
zones of recent mountain building and to 
the margins and interiors of the continental 
plates and ocean basins, and ultimately what 
are the causes and nature of the deformation 
affecting the earth's outer crust and perhaps 
its deeper shells. 

The past year seemed to be a favorable time 
for taking stock of the data accumulated in 
recent years bearing on the distribution of 
earthquakes on the earth, since the spread of 
hostilities continues to eliminate one impor- 
tant seismographic station after another from 
the active list. 



The investigation of the nature of air 
waves, begun by Dr. Gutenberg and Dr. 
Benioff through the use of recording micro- 
barographs, has been continued during the 
past year. 

More data have been collected by Dr. 
Gutenberg and Dr. Richter, but not yet pub- 
lished, on the amplitudes of longitudinal 
waves in deep-focus earthquakes near the 
station at Huancayo. They confirm the results 
found earlier and published in the Bulletin 
of the Seismological Society of America for 
October 1939, indicating that there is a slight 
decrease in the velocity of longitudinal waves 
at a depth of about 80 km. 

The problem of gradual changes of eleva- 
tion of parts of the earth's crust, based upon 
tide-gauge readings, has been given further 
attention by Dr. Gutenberg. The findings 
suggest that there is a small rise in the level 
of all oceans at the rate of about 10 cm. per 
century. Also, the regions around the 
northern part of the Baltic Sea are moving 
upward at the rate of about 1 m. per century. 
The maximum uplift in North America ap- 
pears to be in the neighborhood of Hudson 
Bay and probably exceeds 1 m. per century. 

The registration of local or southern Cali- 
fornia earthquakes was continued uninter- 
ruptedly at the Pasadena Laboratory and the 
six outlying stations, and the results of the 
measurements and interpretation of these 
records proceeded as in former years. These 
data, like those derived from weather bureau 
or astronomical observatory records, gain in- 
creased value as they accumulate, particularly 
since seismic phenomena are spasmodic and a 
true cross section of the earthquake habit of 
a region like southern California is not gained 
from the records of a few years. We wish to 
determine the relative degree of activity of 
the different areas and of the different active 
faults; the depths of the foci of the shocks; 
the relation of the foci to the structure of the 
region; the relation of foreshocks and after- 
shocks to main shocks as to the significance 
of the time relation, the relative positions of 



SPECIAL PROJECTS: TERRESTRIAL SCIENCES 



135 



their foci on the fault, and their energy out- 
puts, these bearing on the sequence of events 
and mechanical processes involved in gener- 
ation of the shock; and the solution of the 
whole problem of the accumulation of stress 
during the intervals between major shocks 
and its release during the earthquake. 

During the year July 1, 1939 to June 30, 
1940, eight shocks of magnitude 4.5 and over 
(sufficient to cause damage in settled areas) 
occurred in the southern California region. 
(This excludes aftershocks of the larger earth- 
quakes.) One of these, on December 27, 
originated near Long Beach and caused slight 
damage in that city. It demonstrates con- 
tinued activity of the source of the destructive 
earthquakes of 1933, the Inglewood fault 
zone. 

The most noteworthy shock of the year was 
the destructive Imperial Valley earthquake 
of May 18. Because of the development of a 
long fault trace with large strike-slip dis- 
placements (up to 15 feet), this is geodynami- 
cally the most significant earthquake in 
America since 1906. The records of the 
southern California stations, including the 
new installation at Palomar Mountain, were 
of great value in locating the epicenter of this 
shock, which is within the visible disturbed 
segment of the fault, instead of at one end, 
as was the case with the Long Beach earth- 
quake of 1933. Owing to a confusion of 
rapidly succeeding earthquakes, no detailed 
study of aftershock seismograms is possible. 
The magnitude of the main earthquake is 
placed at about 6.5. The epicenter was south- 
east of El Centro. There was damage in all 
towns in Imperial Valley, much increased at 
Brawley by an aftershock later in the evening. 
Canals were seriously damaged, with conse- 
quent interruption of water service and some 
loss of crops. The total loss and damage may 
amount to as much as six million dollars. 
Nine persons were reported killed. 

The nearly straight fault trace ruptured the 
surface for a known length of over 40 miles, 
extending from a point between Imperial and 
Brawley in a direction about S. 35 ° E. and 
crossing the international boundary about 8 



miles east of Calexico and Mexicali. The 
fault and attendant phenomena of distortion 
and dislocation were carefully studied in the 
field by Dr. Buwalda and Dr. Richter, and 
the detailed results are being prepared for 
publication. The trace passed within a few 
kilometers and to the east of the instrumental 
epicenter. The southwest side of the fault is 
uniformly displaced northwest with reference 
to the northeast side; vertical displacements 
are generally smaller, and change rapidly 
along the trace, with frequent reversals of 
throw. Near the international boundary hori- 
zontal displacements are 15 feet or more, with 
vertical displacements up to 4 feet. Roads, 
railroads, fences, and canals are offset by these 
amounts. 

No immediate foreshocks occurred. The 
previous day an earthquake originated near 
Twenty-nine Palms. This was felt over a 
wide area, but because of the desert location 
of the epicenter no damage resulted. After- 
shocks of both this and the Imperial Valley 
shock continued for several weeks. During 
this period there were numerous shocks from 
other sources in southern California. One of 
these, on June 4, with epicenter southeast of 
Warner's, damaged the canal system on the 
west side of Imperial Valley. 

A shock of magnitude 6 in northern Cali- 
fornia on February 8, 1940, was well regis- 
tered. 

Many inquiries received at the Seismologi- 
cal Laboratory indicated that some public 
alarm was occasioned by an amateur predic- 
tion of catastrophic earthquakes to occur be- 
tween July 20 and August 5, 1940. Needless 
to say, nothing unusual took place in the 
indicated interval. 

The program of design and construction of 
new types of seismographic equipment under 
the direction of Dr. Benioff made favorable 
progress during the year in spite of consider- 
able diversion of time and energy to national 
defense problems. 

A new short-period galvanometer was de- 
veloped in collaboration with Mr. Lehner. 
The coil of this galvanometer is wound 
directly on the circular mirror. The mirror 



136 



CARNEGIE INSTITUTION OF WASHINGTON 



has two holes, through which the two sus- 
pension ribbons are fastened. Thus the mov- 
ing system has the lowest possible moment of 
inertia, with consequent increase in sensitivity. 

The three-component film recorder was 
nearly completed. The unit has a 10-cycle 
impulse motor drive with stainless steel rib- 
bon belts and pulleys for speed reduction. 
The optical system is similar to previously 
described systems except for the reduced di- 
mensions required by the film. It was found 
desirable to move the galvanometer assembly 
laterally rather than employ the customary 
axial motion of the drum. 

A number of changes were made in con- 
nection with the maintenance and operation 
of the stations. New storage batteries were 
installed in the battery room at the Seismo- 
logical Laboratory. B-battery eliminators 
with automatic change-over switches were 
built for all the 10-cycle drives. The Palomar 
horizontal short-period paper recorder was 
rebuilt to record both components on one 
sheet. Tuning-fork drive assemblies and 
seven moving-coil seismometers were com- 
pleted for the semipermanent station instru- 
ments. The vertical seismometer at Tine- 
maha was moved to a point 500 feet west of 
the station and installed under ground. The 



vertical seismometers at Mount Wilson and 
Riverside were also installed under ground in 
steel tanks. The La Jolla radio receiver was 
rebuilt for higher sensitivity. 

BIBLIOGRAPHY 

Benioff, Hugo, and Beno Gutenberg. Observa- 
tions with the electro-magnetic microbaro- 
graph. Nature, vol. 144, p. 478 (1939). 

Waves and currents recorded 

by electromagnetic barographs. Bull. Amer. 
Meteorol. Soc, vol. 20, pp. 421-426 (1939). 

Gutenberg, B. Tsunamis and earthquakes. 
Bull. Seismol. Soc. Amer., vol. 20, pp. 517- 
526 (1939). 

The structure of the Pacific basin as in- 
dicated by earthquakes. Science, vol. 90, 
pp. 456-458 (1939). 

and C. F. Richter. Depth and geo- 
graphical distribution of deep focus earth- 
quakes. 2d paper. Bull. Geol. Soc. Amer., 
vol. 50, pp. 1511-1529 (1939). 

— New evidence for a change of 

physical conditions at depths near 100 
kilometers. Bull. Seismol. Soc. Amer. 



ol. 



20, pp. 531-538 (1939). 
Deep-focus 



earthquakes in 
America. Proc. 6th Pacific Sci. Cong., pp. 
149-150 (1939). 
Richter, C. F. Earthquake epicenters and struc- 
ture of the Pacific region of North America 
(southern part). Proc. 6th Pacific Sci. 
Cong., pp. 113-118 (1939). 



V. Bjerknes, University of Oslo, Oslo, Norway. Preparation of a wor\ on the application 
of the methods of hydrodynamics and thermodynamics to practical meteorology and 
hydrography. (For previous reports see Year Books Nos. 5-38.) 



Last year's report indicated that the manu- 
script was about ready for publication. Com- 
plete reports are lacking for this year, owing 
to difficulties of communication with Oslo. 
Reports for the first few months stated that 
good progress was being made. 



Dr. C. L. Godske was assisting Dr. Bjerknes 
in completing the manuscript. Dr. E. Hdiland 
was conducting certain experiments in hydro- 
dynamics, the results of which are to be in- 
corporated in the book if completed before 
publication. 



Edward L. Bowles and Jackson H. Cook, Massachusetts Institute of Technology, Cambridge, 
Massachusetts. Research on radio distance measurement. 



In the radio distance measurement project 
being carried on at the Massachusetts Institute 
of Technology under the sponsorship of the 
Carnegie Institution of Washington, appa- 
ratus is now being assembled for testing the 



feasibility of using amplitude modulated high 
frequency (200-300 Mc/s) carrier waves for 
measuring distances ranging from a few 
hundred meters to some tens of kilometers. 
Transmitters and receivers are being con- 



SPECIAL PROJECTS: TERRESTRIAL SCIENCES 



137 



structed for each of two stations so that a 
measuring frequency as high as 1 Mc/s can 
be relayed to and from a remote point and 
its phase delay in transit determined with 
some precision at the station of origin. It is 
planned to adjust the measuring frequency 
until a simple reference phase relation (o° or 
180 ) between outgoing and incoming waves 
is obtained. Measurement of distance will 
thus resolve itself into measurement of fre- 
quency. 



An effort is being made to incorporate 
conventional circuits and circuit elements in 
the apparatus, in the interest of simplicity 
and dependability. 

It is expected that by the latter part of 
December 1940 the component parts of this 
system including the free space link will have 
been tested. On the outcome of these tests 
will depend the next steps to be taken in the 
investigation. 



Joseph C. Boyce, Massachusetts Institute of Technology, Cambridge, Massachusetts. Research 
in the spectroscopy of the vacuum ultraviolet. (For previous report see Year Book No. 38.) 



This research continued under a grant 
from the Carnegie Corporation of New York 
to the Carnegie Institution of Washington. 

The program of mapping the spectra of 
the elements in the vacuum ultraviolet has 
gone forward, but is still confined to the 
wave-length range from X2000 to A1200. In 
spite of two interruptions to the work, a con- 
siderable number of additional spectrograms 
have been obtained. The parallel Works 
Progress Administration project for the meas- 
urement of the spectra has handled more 
than half of these spectrograms. 

The old pumping system on the Carnegie 
spectrograph had given increasing trouble, 
and last autumn it was replaced by a faster 
system. A self-fractionating pump of 200 
liters per second capacity, manufactured by 
Distillation Products, Inc., was obtained 
secondhand from another research group at 
this Institute. It has been mounted with a 
new large refrigerating trap connecting to 
the spectrograph. In use it has reduced from 
two hours to an hour the time required to 
evacuate the spectrograph. A system has been 
prepared for the purification and handling of 
inert gases, particularly to supply helium for 
use with the hollow-cathode light source. 

During the year 72 spectrograms have been 
made, with various exposure times and with 
and without wave-length standards, distribut- 
ed among the following elements: Ti, Fe, 
Co, Cu, Zr, Ru, Rh, Ag, W, Pt, Au, Th. 



The spectrograms are measured on the Harri- 
son automatic comparator. Six runs are 
made on each exposure, three in each direc- 
tion. The record films from the comparator 
are read by W. P. A. workers, and the read- 
ings entered on cards and averaged by them. 
This process has now been completed for 
40 exposures, with an average number of 
about 1000 lines per exposure. 

Particular attention has been paid to meas- 
urements of iron, copper, and silver. Pressed- 
powder electrodes of mixtures with one or 
more of these three elements are used to pro- 
vide wave-length standards when other ele- 
ments are under investigation. Measurements 
are ultimately referred to the iron standards 
of Green in the region from X2000 to A1550 
and to the copper standards of Shenstone at 
shorter wave lengths. Hollow-cathode ex- 
posures with copper, now in progress, will 
be necessary to tie in our copper lines with 
Shenstone's standards. 

Data on rhodium have been turned over to 
another member of the laboratory, who is 
engaged in the analysis of the Rh II spec- 
trum. He reports that a considerable number 
of lines fit into and extend the term array 
which had been started on the basis of data 
from more accessible wave-length regions. 
Data on ruthenium and thorium are ready 
for two other local investigators who are 
working on the spectra of these elements. 
Data on rare-earth spectra are urgently 



138 



CARNEGIE INSTITUTION OF WASHINGTON 



needed to complete studies of these elements 
at longer wave lengths, in progress in this 
laboratory. The first type of light source 
tried was not satisfactory for the vacuum 
ultraviolet, and other methods of exciting 
these spectra will have to be developed. 

A request for the cobalt data has come 
from Princeton University. Preliminary data 
on gold have been sent to the University of 
Michigan. Investigators at the National 
Bureau of Standards have requested data on 
three elements not listed above. These ele- 
ments will be given priority in the coming 
year. A preliminary report on this program 
of investigation was made in April at the 
Washington meeting of the American Physi- 
cal Society (Physical Review, vol. 57, p. 1073, 
1940). It was there announced that spectra 
and wave-length lists would be made available 
to investigators at other institutions. Contacts 
have been made with several observatories 
active in astronomical spectroscopy. The 
number of laboratories in this country en- 



gaged in the analysis of atomic spectra is 
rather small, but this circumstance helps in 
the coordination of work. Almost all of these 
laboratories are represented on the National 
Research Council Committee on the Line 
Spectra of the Elements, to which committee 
Dr. Boyce was recently added. 

An article on the general field of spectros- 
copy in the vacuum ultraviolet has now been 
completed and will appear in an early num- 
ber of the Reviews of Modern Physics. It 
includes the critical bibliography of published 
atomic spectra mentioned in last year's report. 

Dr. Lore Misch, research assistant under 
the grant, resigned on April 1. Her place was 
taken June 1 by Miss Pauline Pitkin. Mr. 
N. H. Moore was engaged as a temporary 
additional assistant for the summer months 
of 1940. 

BIBLIOGRAPHY 

Boyce, J. C., and L. Misch. Line spectra in the 
vacuum ultraviolet. Phys. Rev., vol. 57, p. 
1073 (1940). 



F. A. Perret, Martinique, French West Indies. Volcanological investigations. (For previous 
report see Year Book No. 38.) 



Volcanological studies in the British West 
Indies and in Martinique have continued 
with aid of a grant from the Carnegie Corpo- 
ration of New York. After the virtual ending 
of the crisis at Montserrat and publication by 
the Institution of a third monograph by Dr. 
Perret, it was understood that a fourth vol- 
ume would be forthcoming. This is to be a 
record of all observations made in the course 
of forty years of dedication to this work, in 
the study of many volcanoes in times of the 
greatest activity, involving two trips around 
the world. The observations will be classified 
as to morphology, phenomena, products, etc., 
instead of being confined to the study of 
some one event; and the whole will consti- 
tute a volume unique in character. It will 
be a record of actual conditions, personally 
studied at close range and revealed in quite a 
special manner by an intensively acquired 
photographic documentation of every detail. 



Field excursions have been made at Mar- 
tinique for clearing up certain points which 
always are raised the moment writing is 
begun, and trips were made to St. Lucia, 
where investigation is under way regarding 
the important soufriere, so far most imper- 
fectly studied, and the Pitons, regarding 
which a new thesis is being developed. A 
summer visit to New York was necessary, 
especially as war conditions render photo- 
graphic work at Martinique impossible. 
Notes and materials and a great number of 
negatives are being converted into book ma- 
terial. Most of the writing will be done in 
Martinique with library facilities at hand, and 
Dr. Perret expects to return to New York in 
the spring of 1941 to complete the undertak- 
ing. More field work will be needed, and 
some material from St. Lucia has been ex- 
amined at the Geophysical Laboratory of the 



SPECIAL PROJECTS: TERRESTRIAL SCIENCES 



139 



Institution. In a word, the new book is being Volcanology at the Eighth American Scien- 

made up, with all that this involves, and new tific Congress, held in Washington in May. 

knowledge — whose acquisition never ends — Since he was unable to be present, the paper 

is being gained. was kindly read for him by a colleague, 

In the spring of 1940, Dr. Perret was in- who expanded it by references to former 

vited a submit a paper at the Symposium on observations. 



DIVISION OF PLANT BIOLOGY 

Central Laboratory located at Stanford University, California 
H. A. SPOEHR, Chairman 



For many years it has been a matter of 
speculation whether the great multiplicity of 
substances found in plants arises essentially 
from a single parent substance which is pro- 
duced in the photosynthetic process. This 
multiplicity of substances includes, first of 
all, the principal groups of foodstuffs, the 
carbohydrates, fats, and proteins which form 
the basis of all human nutrition. It also in- 
cludes the great variety of substances which 
constitute drugs, rubber, pigments, fibers, and 
the almost countless array of complicated 
chemical substances which are found in 
plants. It has been very generally assumed, 
and with apparently good reason, that the 
product of photosynthesis is a carbohydrate, 
and that all the other organic compounds 
found in plants are formed from this carbo- 
hydrate through the diverse biosynthetic re- 
actions which the plant is capable of carry- 
ing out. 

That the plant possesses a remarkable 
capacity for synthesis, probably far greater 
than that of animals, is a familiar fact and 
is exemplified by the ability of plants to 
synthesize their nitrogenous components from 
simple inorganic compounds. Yet it is of 
considerable theoretical and practical impor- 
tance to determine whether the photosyn- 
thetic process results in a single compound, 
of the nature of a carbohydrate, or in a variety 
of substances of which carbohydrates consti- 
tute the dominant or major portion. This 
cannot be determined through ordinary ana- 
lytical methods. 

It may now, however, be possible to gain 
some light on this problem by the use of 
plants which are completely lacking in the 
normal photosynthetic mechanism; that is, by 
nourishing such plants artificially with partic- 
ular organic compounds, and comparing their 
development with that of their analogues 
possessing the normal capacity for photo- 
synthesis. Such comparable material is 



offered by pure albino maize plants, devoid 
of chlorophyll and unable to carry out photo- 
synthesis, and the normal green plants which 
are used as controls. 

Because of the fact that the albino plants 
are incapable of manufacturing their own 
food by means of photosynthesis, they are 
able to live only until the food material stored 
in the seed has been exhausted, and then die 
of starvation. This is usually a matter of ten 
to fourteen days after germination of the 
seeds. During the past year methods have 
been developed for the artificial nutrition of 
albino plants which makes it possible to keep 
such plants alive for at least four months. 
While there are still many matters of tech- 
nique to be improved, it is possible to use 
the method for a study of the organic nutri- 
tion of such plants with a view to determin- 
ing the metabolic changes which particular 
organic nutrients undergo in the plant. 

There are obviously many aspects of the 
development of plants which must be fol- 
lowed through by this means in order to gain 
a comprehensive understanding of the meta- 
bolic changes which take place. Attention is 
being given primarily to the nutritional phe- 
nomena, although this study will ultimately 
have to be supplemented by morphological 
and histological investigations. The rate of 
development of artificially nourished albino 
plants is in general parallel to that of normal 
plants growing in the field; that is, the num- 
ber of leaves produced is about the same in 
the two sets of plants. But the total mass of 
tissue and dry weight which is produced in 
the artificially nourished plants is considerably 
less than that in the normal plants. For this 
reason attention has been given to the ability 
of the artificially nourished plants to produce 
the materials constituting the structural ele- 
ments of the corn plant, more particularly 
the uronides and pentoses. From the evidence 
thus far obtained it would appear that the 



141 



142 



CARNEGIE INSTITUTION OF WASHINGTON 



albino plants are capable of producing these 
materials from sucrose as the only organic 
nutrient. The intermediate steps in a bio- 
synthesis such as the formation of uronides 
from sucrose will, of course, need further 
elaboration, and this process is cited here as 
typical of the metabolic changes which are 
being followed. The method is applicable to 
the study of a wide variety of substances, 
including the vitamins and hormones which 
have recently been demonstrated to play so 
important a part in the growth and develop- 
ment of both plants and animals. It is already 
clear that considerable effort will have to be 
devoted to the development of special methods 
of analysis in order to follow quantitatively 
the production of various materials within the 
albino plants, and this work is being pushed 
in several directions as rapidly as possible. 

Investigation of the nature of the products 
formed in photosynthesis is also being pur- 
sued from quite another angle. This study 
has as its objective the following of the carbon 
dioxide from the atmosphere surrounding the 
leaf, through the various combinations and 
transformations it undergoes, to its reduction 
and elaboration into complex organic matter. 
Thus far the first steps only in following this 
course have been taken. Following the course 
of carbon dioxide as it enters the leaf has been 
very difficult because the living leaf presents 
a rather unusual complexity. Not only does 
the leaf absorb carbon dioxide from the at- 
mosphere during photosynthesis, but it is 
also constantly producing carbon dioxide 
within its cells. Consequently it has previ- 
ously been impossible to distinguish between 
the carbon dioxide which enters directly into 
the photosynthetic process from the atmos- 
phere and the carbon dioxide which arises 
from sources within the leaf. 

A means has now been found for "label- 
ing" carbon dioxide through the use of radio- 
active carbon. By employing radioactive car- 
bon dioxide in the atmosphere surrounding 
the leaf, it is possible to follow the course of 
its reactions within the leaf with much greater 
accuracy than heretofore. Through the co- 
operation of the staff of the Department of 



Terrestrial Magnetism, Dr. J. H. C. Smith 
has been able to secure radioactive carbon 
dioxide and carry forward experiments with 
this material which supplement his earlier 
studies with ordinary carbon dioxide. Though 
the experiments have thus far been confined 
to a single species, it has been possible to 
demonstrate that in the sunflower leaf the 
carbon dioxide first enters a kind of reservoir 
through three types of reaction: solution of 
the carbon dioxide in the water of the sap, 
reaction with buffer substances to form bicar- 
bonate ion, and reaction with insoluble car- 
bonates to form soluble bicarbonates. In 
addition to these primary reactions, a small 
amount of carbon dioxide is also converted 
into organic compounds. The significance of 
this reaction, as well as the nature of the 
product, has as yet not been established. All 
these reactions occur in the dark. The fact 
that the carbon dioxide absorbed in the dark 
can be converted into organic material by 
illumination indicates that the absorption of 
carbon dioxide for use in the photosynthetic 
process is independent of the photochemical 
reaction. 

Although the use of radioactive carbon 
dioxide in the investigation of the mechanism 
of photosynthesis requires the development 
of new techniques, it is proving to be one of 
the most useful tools which have yet become 
available. It is quite possible that if long-life 
radioactive carbon becomes available for these 
investigations it may prove to be of even 
greater usefulness. 

One of the greatest lacks in our knowledge 
of photosynthesis is an understanding of the 
type of physical-chemical system and some of 
the essential components which go to make 
up the photosynthetic apparatus of the plant. 
It is true that what may be termed the grosser 
aspects have been determined; we know a 
good deal about chlorophyll and about the 
carotenoid pigments, the requisite raw ma- 
terials; something about the products; and a 
good deal about how the reaction is affected 
by various environmental factors which influ- 
ence the rate of photosynthesis. But because 
of the extraordinary sensitivity of the photo- 



DIVISION OF PLANT BIOLOGY 



143 



synthetic process, and the remarkable ease 
with which it is completely stopped by even 
minor disturbances, we know virtually noth- 
ing concerning the more labile parts of the 
apparatus and the role of the less easily acces- 
sible parts of the cell constituents. In the 
elaborate speculative hypotheses which are 
being formulated to explain the mechanism 
of the photosynthetic reaction, a heavy burden 
is borne by the assumption of elements in the 
apparatus about which nothing is known. 
Useful as such hypotheses may be for further 
investigation, their ultimate value depends 
upon the definite establishment of the type 
of physical-chemical system which is involved. 

For this reason investigations have been 
continued on the enzymes which influence 
the reactions of the pigments and on the state 
of the pigments in the leaf. That pigments 
which have been isolated from leaves and 
subjected to careful study differ in some 
fundamental aspects from their state in the 
living plant is now realized. It is difficult to 
determine the causes for this discrepancy 
because of the extreme sensitivity of some of 
the elements of the pigment systems. Some 
of the changes which the pigments undergo 
on isolation from the plant are obviously due 
to destructive oxidative action which is initi- 
ated the moment the pigment-containing cells 
are killed or even injured. 

During the past year the mode of action 
of some of these enzyme systems has been in- 
vestigated in greater detail. One of the most 
striking features of such systems is their great 
specificity, demonstrating that they are de- 
pendent upon particular atomic groupings 
within the molecules affected. To gain an 
understanding of the chemical reactions 
which are involved in so complex a mecha- 
nism as photosynthesis, it is obviously not 
sufficient to know the reactions of the indi- 
vidual components as isolated in the pure 
state. In the leaf the reactions are inter- 
related and interdependent, and examples 
have now been found which demonstrate 
that certain of these processes occur primarily 
when associated with some other reaction 
involving materials of a very different nature. 



Illustrative of this principle is an investigation 
which has been carried out to test whether 
hexenaldehyde is actually the first product, 
or an early stage, in photosynthesis, as has 
been proposed by one school of thought. It 
has been found that this substance, which 
has been obtained from a large variety of 
leaves, is actually produced by enzymatic 
oxidation during the process of extraction 
and normally exists in the leaf only in very 
minute amounts, if at all. 

The investigations of the photosynthetic 
efficiencies by Drs. Emerson and Lewis have 
been considerably extended during the past 
year, and the results have helped to clarify 
this much-debated and theoretically impor- 
tant problem. On the basis of an extended 
series of precise measurements, it now ap- 
pears highly probable that the high efficien- 
cies which had been previously obtained are 
subject to serious doubt. This questioning of 
the correctness of the high efficiencies has 
resulted from a very critical experimental 
examination of the methods which are used 
for these investigations and a scrutiny of the 
assumptions upon which the computed effi- 
ciencies are based. The examination of 
methods has given indication that the high 
efficiencies represent results obtained under a 
rather special set of conditions, and that, 
although these values are reproducible, they 
may not give a true measure of photo- 
synthesis. 

Measurements of efficiencies have been 
made with eleven different organisms, repre- 
senting a fairly diverse group. The values 
for seven of these fall within a range of about 
10 per cent, and the others do not differ 
greatly. The results show a quantum number 
of 8 to 12, instead of 4, which was the value 
obtained from the first careful measurements 
of efficiency which were made. The signifi- 
cance of the newly determined quantum 
number lies, of course, in the fact that it 
indicates that 10 quanta of light energy are 
used for the production of each molecule of 
oxygen and presumably for the reduction of 
each molecule of carbon dioxide to carbo- 
hydrate in the photosynthetic process. The 



144 



CARNEGIE INSTITUTION OF WASHINGTON 



high efficiency represented by the quantum 
number 4 was particularly attractive from the 
theoretical viewpoint, because it gave indica- 
tion that four steps were involved in the 
reduction of carbon dioxide to carbohydrate, 
and the sequence of the chemical steps in 
such a series of reactions could be dealt with 
on the basis of known chemical principles. 
A value of 10 quanta permits of so many 
complications that speculation as to the pos- 
sible course of the chemical reactions becomes 
so tremendously involved as to be of little 
profit. 

The establishment of a value for the effi- 
ciency of the photosynthetic process is never- 
theless of great importance, especially as it 
has been shown to be a characteristic property 
of photosynthetic organisms. It has been 
found to be much less dependent upon cul- 
ture and experimental conditions than had 
been supposed. Similarly, the age of the 
organisms seems to influence the value very 
little. Although the rate of respiration varies 
greatly with temperature, this has relatively 
little effect on the efficiency. It is, therefore, 
highly probable that further development of 
the methods for measuring efficiencies will 
become one of the most useful means of 
penetrating more deeply into the mechanism 
of the chemical reactions which are involved 
in the photosynthetic process. 

The investigations in experimental tax- 
onomy deal with the forces that govern the 
appearance, distribution, and evolution of 
plants under natural conditions. During the 
year considerable effort was spent on a study 
of the local races of which species are com- 
posed, and of the genetic systems which 
characterize species and their regional races. 

Species are made up of many intermittent 
and variable populations, each composed of 
many biotypes or individual variants. The 
populations have very little chance for inter- 
breeding, because usually they are separated 
by some distance geographically. Accord- 
ingly, they often become morphologically dis- 
tinguishable and represent very early stages 
of evolutionary differentiation within the 



species. Populations within • major climatic 
regions tend to become arranged into race 
complexes of characteristic reaction and ap- 
pearance, the ecotypes. The number of eco- 
types in a species depends in part upon the 
number of climatic zones it occupies. Differ- 
ences between ecotypes depend upon series of 
genes affecting each character, rather than 
upon single pairs of genes. Some variations 
within species seem to adapt plants to various 
kinds of environment, others appear to ex- 
press only the abundance of possibilities con- 
nected with the unfolding of life, but there 
are no basic differences between these two 
kinds of variation. 

The separation of species by the develop- 
ment of genetic barriers is a secondary phe- 
nomenon, which is of great importance for 
evolution but of no immediate consequence 
for adaptation. The barriers differ in distinct- 
ness, and a dynamic picture of the gradual 
evolutionary process is obtained through the 
discovery of barriers between species in vari- 
ous stages of separation. Very strong barriers 
were discovered, for example, between Layia 
heterotricha and its closest relatives; even its 
first-generation hybrids were very weak, al- 
though the chromosome number of the par- 
ents is the same. On the 6ther hand, very 
slight barriers were observed in the Madia 
sativa complex. 

Artificial production of new species 
through hybridization succeeded in two in- 
stances. This was done by the addition of 
all the chromosomes of both parental species, 
which were separated by strong genetic 
barriers. 

In the selection experiment a recombina- 
tion of morphological and reactional charac- 
teristics took place. This indicates that genes 
determine both morphologic and physiologic 
characteristics of climatic races. This experi- 
ment also shows that certain plant groups 
have latent evolutionary resources which can 
be released by crossing races from very dif- 
ferent climates. 

The experiments lead to the concept that 
environment acts as a sieve that sorts out 
hereditary forms into suitable ecological 



DIVISION OF PLANT BIOLOGY 



145 



niches by eliminating types not in harmony 
with it. Genes apparently govern physiologic 
processes which, in turn, determine a plant's 
reactions to different environments, as seen 
in the modifications of the transplant experi- 
ments. But how the physiologic processes are 
related to the environmental modifications on 
the one hand, and to the heredity of the race 
on the other, is still entirely unknown. 

The desert investigations carried on for the 
past seven years have been part of a compre- 
hensive program for the botanical study of 
the entire arid portion of North America. 
This region embraces four areas with distinc- 
tive physical and biological features. The 
program provides that each of the four shall 
be investigated separately and the results pub- 
lished independently. Field work has been 
completed in the Sonoran Desert and the 
floristic and ecological results are being pre- 
pared for publication. In the Chihuahuan 
Desert field work has been carried on for two 
seasons, and three more years will be needed 
to complete the project. The study of the 
Mojave and Great Basin deserts will require 
no new work on the flora, which has already 
been adequately investigated; and the study 
of their vegetation will be facilitated by the 
familiarity and accessibility of the two areas. 
The aims of the work are a complete enu- 
meration of the plants of the North American 
Desert, an adequate picture of the natural 
vegetation as modified by geographical and 
local differences of climate and soil, and a 
fuller knowledge of the features of structure, 
function, and environmental relations by 
which desert plants are marked. From these 
results it will be possible to learn more of the 
history of the present plant population of the 
desert. 

Reporting on his cooperative investigations 
with agricultural agencies, Dr. Clements 
points out that it is significant of the eco- 
logical approach to problems of soil conser- 
vation that the main features of the plan 
should have been brought out by ecological 
studies. Of much value for forecasting yields 



in a particular field, farm, or range is the 
record of soil moisture, which has already 
taken much of the hazard out of wheat farm- 
ing. The first of such records were made in 
dynamic ecology more than forty years ago. 
The use of small close trenches to replace 
pasture furrows and of small subterraces to 
promote infiltration and control erosion and 
flooding was recommended some seven years 
ago and is now becoming standard practice. 

The value of tall headed stubble and light 
subtillage was discovered in the course of 
studying the natural succession in fields 
abandoned by the "suitcase farmer" and bids 
fair to effect the greatest saving of all in soil 
water. Dr. Clements is of the opinion that 
the elements of the plan are nearly as essential 
to the task of regrassing several million acres 
of repurchased farms as they are to successful 
crop production. In addition, the specializa- 
tion of grass covers for the different climates 
and regions is based in the first instance upon 
the field studies of climax and succession. 
Equally important, Dr. Clements believes, is 
the measurement of adaptability to various 
regions and sites of more than a hundred 
species of grasses and legumes and several 
times as many climatic and edaphic strains. 
The broad foundation for this has been laid 
in twelve different habitats at the Alpine 
Laboratory and an equal number of factor 
series at Santa Barbara, as a part of the pro- 
gram in adaptation and origin. These meth- 
ods are now being extended to the main 
nurseries of the Soil Conservation Service, in 
large measure under young ecologists trained 
at the Alpine Laboratory. 

With the completion of Dr. R. W. Chaney's 
study of the Shanwang flora from Shantung 
Province, China, the Miocene vegetation of 
eastern Asia may for the first time be effec- 
tively compared with that of western North 
America. A considerable number of species 
show close relationship, and the dominant 
genera are essentially the same on both sides 
of the Pacific. The conclusion is reached that 
the mild, moist climate which was prevalent 
in western America during the Miocene also 



13 



146 



CARNEGIE INSTITUTION OF WASHINGTON 



characterized North China. Distinctive ele- 
ments in the fossil floras of the two continents 
suggest that while a land connection may still 
have existed between them, probably across 
Bering Strait, there was a climatic barrier at 
the north which prevented any complete 
interchange of floras. Intercontinental com- 
parisons of this sort throw much light upon 
the history of climate, and upon the factors 
responsible for its change during geologic 
time. 

Continuation of studies of the Tertiary 
vegetation of Oregon has centered on the 
Pliocene floras from The Dalles and Trout- 
dale. Additional material has been collected, 
in cooperation with the Geological Society of 
America, which indicates a transition from 
the mild climates of earlier Tertiary time to 
the more rigorous climate of today. This 
work in Oregon is closely related to the 
studies of Dr. Axelrod on the Pliocene of 
California and Nevada. 

Preliminary field work in the area south of 
the John Day Basin has involved the collec- 
tion of plant fossils similar to the Mascall 
flora. Geologic studies indicate that the John 
Day sequence of volcanic sediments and lavas 
is found in Harney County, and emphasize 
the importance of the section in the John Day 
Basin as a means of interpreting stratigraphy 
in other parts of western America. 

During the past year one of the first projects 
undertaken by the Carnegie Institution was 
terminated. The Desert Laboratory has been 
in continuous operation for thirty-eight years; 
it may, therefore, be of interest to review the 
origin and the activities of this project of the 
Institution very briefly. 

The Desert Laboratory was started in 1902 
on recommendation of the Advisory Com- 
mittee on Botany. In the report of this com- 
mittee, submitted to the Board of Trustees of 
the Carnegie Institution, it was stated: 

There should be established at some point in 
the desert region of the southwestern United 
States a laboratory for the study of the life 
history of plants under desert conditions, with 
special reference to the absorption, storage, and 



transpiration of water. Although there are many 
botanical laboratories in the humid portions of 
the temperate regions, as well as several 
marine laboratories and tropical laboratories de- 
voted in whole or in part to botanical research, 
a desert botanical laboratory exists nowhere in 
the world. Yet the phenomena presented in 
the adaptation of plants to desert conditions are 
among the most interesting and significant, from 
an evolutionary point of view, of any in the 
whole realm of botany. 

The economic ground for the establishment 
of such a laboratory is the enormous develop- 
ment of population and industries that is bound 
to take place in our arid regions during the 
next hundred years. The basis of that develop- 
ment is agriculture, both with and without 
irrigation. At the present time comparatively 
little is known about the peculiar fundamental 
processes of plant growth under the unusual 
conditions surrounding plant life in that region. 

During the past thirty-eight years the 
Desert Laboratory has undertaken extensive 
investigations of the distribution and func- 
tioning of desert plants, the results of which 
have been set forth in over four hundred 
journal articles, monographs, and books. 
Correlative investigations have been made in 
the desert regions of Algeria, Libya, Australia, 
and South Africa. The studies of Dr. Forrest 
Shreve and his collaborators in the desert 
areas of Baja California, Sonora, and Chi- 
huahua, Mexico constitute a logical culmina- 
tion of this extensive project, and arrange- 
ments have been made for the completion of 
this work. 

It has been the aim of the Desert Labora- 
tory to carry out the work of investigation of 
desert conditions on as fundamental a basis 
as possible. The fact that arid and semiarid 
regions constitute one-third of the earth's 
land surface and almost one-fourth of the 
area of continental United States indicates the 
magnitude of the task. The published results 
emanating from the Desert Laboratory have 
contributed materially to a better understand- 
ing of the characteristics which are common 
to all deserts, of the relations between different 
desert areas, and of the evolution and move- 
ments of desert plants. Of importance in this 
connection has been the study of the climatic 



DIVISION OF PLANT BIOLOGY 



147 



conditions of the desert in relation to the 
distribution and survival of plant life. The 
results from the investigations have also con- 
tributed materially to an understanding of 
the problems involved in the formulation of 
a scientific and rational program of land use. 

The scientific problems underlying the use 
of arid and marginal lands can no longer be 
considered academic. They are now emi- 
nently practical and even urgent. Their 
importance has been generally recognized, 
and their study is now being promoted in- 
tensively by various tax-supported agencies. 
The growth of these agencies, as in fact the 
development of our arid regions, has probably 
greatly exceeded the expectations of thirty- 
eight years ago. These agencies are for the 
most part on a permanent basis, with ample 
and growing financial support, and definitely 
committed to a continuing study of the prob- 
lems of the regions. Many of these problems 
are also being studied with a view to their 
practical significance and consequently have 
become so extensive and inclusive of other 
branches of science that means far beyond 
those of the Institution are required. 

During the past year the land, buildings, 



equipment, and most of the library, consti- 
tuting the Desert Laboratory, have been 
donated to the U. S. Forest Service to become 
the headquarters of the Southwestern Forest 
and Range Experiment Station. It is believed 
that the continuing interest of the Forest 
Service in the type of problem to which the 
work of the Desert Laboratory has been de- 
voted assures progress in the field in which 
the Carnegie Institution of Washington made 
this pioneer effort. The domain of the Labo- 
ratory near Tucson, Arizona, consisting of 
an area of land which has been protected 
for many years, and which now probably 
represents a condition of vegetation much 
like that found by the early Spanish explorers, 
is of unusual interest and value, and will be 
perpetuated. This is another instance of the 
interesting and gratifying relations which the 
Carnegie Institution of Washington has en- 
joyed with the U. S. Forest Service. 

In conformity with the policy of the Insti- 
tution to dispose of property which has served 
its usefulness, and in the interest of economy, 
the buildings and land constituting the 
Coastal Laboratory at Carmel, California 
were sold during the past year. 



BIOCHEMICAL INVESTIGATIONS 
H. A. Spoehr, J. H. C. Smith, H. H. Strain, and H. W. Milner 



The Organic Nutrition of Plants 

The development of methods for the arti- 
ficial nutrition of plants has progressed so 
that it has been possible to keep albino maize 
plants alive for over four months. This 
probably does not represent a limit in the 
length of time the plants can be maintained. 
Such plants are, of course, completely lacking 
in the normal photosynthetic mechanism pos- 
sessed by green plants. After the stored food 
contained in the seed of the albino plants has 
been exhausted, they die, unless food material 
is supplied by artificial means. The rate of 
development of the plants under such arti- 
ficial nutritional conditions is not very dif- 
ferent from that of normal green plants, 
which derive their nutrition through the proc- 



ess of photosynthesis. Thus the albino plants 
produced fifteen leaves in a period of 100 to 
115 days. Normal green plants, grown in the 
field from seed from the same ears which pro- 
duced the albinos, bore on the average the 
same number of leaves. With the methods 
for artificial feeding which have thus far been 
developed, the size which the plants attain 
is considerably below that of normal plants, 
running to about 50 cm. in height with a leaf 
width of 2 to 3 cm. 

Various substances have been used as or- 
ganic nutrients; of these sucrose has given the 
best results. Contrary to the experience of 
other investigators with albino plants, it has 
been found that under the conditions of nutri- 
tion followed in these investigations the plants 



i 4 8 



CARNEGIE INSTITUTION OF WASHINGTON 



produce abundant starch in the leaves when 
fed sucrose. Some organic substances which 
have been considered sufficient sources of car- 
bon nutrient, as for example glycerine, have 
proved to be inadequate for the prolonged 
development of albino maize. It must be 
emphasized, however, that it is too early to 
draw definite conclusions regarding the rela- 
tive value of different compounds for the 
development of plants which have been de- 
prived of their photosynthetic nutrition. Ex- 
periments are also still in progress on the 
necessity of including various accessory fac- 
tors such as hormones, in order to attain 
development approaching that of a normal, 
photosynthetically active plant. These experi- 
ments require rigorous control and analysis. 

The albino plants which have been grown 
with organic nutrients exhibited considerable 
abnormality in the development of the in- 
florescences. The pistillate inflorescence de- 
veloped slowly and with very long silk. Thus 
far no staminate inflorescences have been 
observed. Little attention has as yet been 
given this aspect of the problem of organic 
nutrition, because the simpler problems of 
nutrition and growth of the albinos have 
naturally demanded first attention. 

Another method of organic nutrition which 
has been used depends upon the feeding of 
green plants kept in the dark. For this pur- 
pose sunflower plants have been used chiefly. 
These are permitted to grow in the light until 
they have produced six to eight leaves, and 
are then placed in the dark. Such plants can 
maintain themselves on stored food material 
for 10 to 14 days, but then die. When fed 
with organic nutrients in the dark, the plants 
have been kept alive for over 2 months. The 
new leaves and stems produced under these 
conditions are free of chlorophyll, and the 
plants grow tremendously in length. Flower 
buds are developed and these open to the 
typical yellow flowers, but are entirely lacking 
in chlorophyll. One of the striking peculiari- 
ties of these artificially fed plants is their 
almost complete lack of pith. There still re- 
main many features of technique to be per- 



fected before quantitative arid analytical re- 
sults of value can be expected. But the 
general method is of sufficient promise to 
warrant further effort. 

One of the objectives in the investigations 
on the organic nutrition of albino plants was 
to determine whether pentose sugars and 
uronides are a product of photosynthesis or 
whether these substances arise from hexoses 
in the metabolism of the plant. It has been 
suggested on purely theoretical grounds that 
uronides may be the result of oxidation of the 
terminal carbinol group of the hexose units 
of a polysaccharide. Similarly, the formation 
of pentoses in plants may arise from this type 
of progressive oxidation and the subsequent 
decarboxylation of the uronides. The pentoses 
and uronides are important constituents of 
plants and they enter into the composition of 
a considerable portion of the structural ele- 
ments. As yet very little is known regarding 
the mode of formation of these substances, 
and such theories as have been advanced to 
account for their formation are based pri- 
marily upon speculation and conjecture. In 
albino maize plants which had been kept 
alive for three months by feeding sucrose as 
the only source of carbon, the uronic acid 
content, as percentage of the dry matter of 
the leaves, was found to be about twice that 
in normal plants, grown in the light. 

Although many features of the interrelation 
between food material and the formation of 
structural elements such as the uronides and 
pentoses are still to be worked out, the experi- 
ments indicate that the latter substances can 
be formed from sucrose as a primary source 
of organic nutrition. What chemical trans- 
formations the sucrose may undergo in the 
course of the biosynthesis of the uronides 
remains to be established. That the albino 
plants are capable of synthesizing starch from 
sucrose in the dark has already been 
mentioned. 

There are some indications that under cer- 
tain conditions starch may be a source of 
uronic acid formation in the plant through 
the oxidation of the terminal primary alcohol 



DIVISION OF PLANT BIOLOGY 



I 49 



groups to carboxyl groups. Leaves of plants 
which produce an abundance of starch 
through photosynthesis, such as the sunflower 
and tobacco, have been found to have a 
uronic acid content of 7 to 12 per cent of the 
dry leaf material, though no genetic relation 
between these two classes of substance has 
yet been established. 

An effort has been made to achieve this 
type of oxidation of starch in vitro. Of the 
various oxidizing agents tried, the most 
promising proved to be hydrogen peroxide 
in the presence of a small amount of ferrous 
sulphate. It was found to be of considerable 
advantage to use starch preparations of high 
solubility. For this purpose starch prepara- 
tions were used which had been ground 
extremely fine in a pebble mill with agate 
marbles for 1500 to 2000 hours. Such prepa- 
rations of starch when stirred up with 2 to 
5 times their weight of cold water yield a 
clear mucilage which is easily soluble in hot 
water. Oxidation of such solutions of starch 
with 2.25 mols hydrogen peroxide per glucose 
unit yielded, besides small quantities of car- 
bonic, formic, and oxalic acids, two fractions 
which were insoluble and one which was 
soluble in ethanol. 

The chemical identity of the substances 
which were obtained in these experiments has 
not yet been established, and some of the 
fractions in all probability are mixtures. Ana- 
lytical results indicate that these products are 
complex organic acids. As the solubility in 
alcohol increases, equivalent weights range 
from 585 to 318, specific rotation from 
-fi09°~to +53.5°, and respective uronide 
content from 30 to 55 per cent. These sub- 
stances reduce Benedict's solution, yield fur- 
fural on hydrolysis, and reduce alkaline iodine 
solution. They are easily destroyed by very 
mild chemical treatments, such as efforts to 
hydrolyze them to their simpler component 
molecules. The investigations are being con- 
tinued with a view to determining whether 
these products of the oxidation of starch are 
true uronic acid compounds or are some 
modified form of this group of substances. 



The Use of Radioactive Carbon Dioxide 
in Photosynthesis 

During the past year advantage has been 
taken of the availability of radioactive carbon 
to investigate the chemical mechanism for 
the absorption of carbon dioxide by unillumi- 
nated sunflower leaves and the utilization of 
this absorbed carbon dioxide in photosyn- 
thesis. This work was made possible through 
the generous cooperation of the Department 
of Terrestrial Magnetism, whose high-voltage 
equipment was used for the preparation of 
the radioactive carbon, and of Mr. D. B. 
Cowie, Research Fellow of the National 
Cancer Institute. 

In previous experiments it had been found 
that the amount of carbon dioxide absorbed 
by unilluminated sunflower leaves could be 
completely removed by evacuation. This was 
evidence for the complete reversibility of the 
process. When, however, these absorption 
experiments were repeated with radioactive 
carbon dioxide, it was found that although 
an amount of carbon dioxide was removed 
by evacuation which was equal to the amount 
absorbed, the leaf retained approximately 25 
per cent of the radioactive carbon it had 
absorbed. This observation was interpreted 
to mean that the carbon dioxide absorbed by 
the leaf became a part of a carbon dioxide 
reservoir, and exchanged freely with the car- 
bon dioxide contained therein. By acidifica- 
tion and evacuation all but a small part of the 
radioactive carbon was removed from the 
leaves. This was evidence that most of the 
radioactive carbon retained by the leaves was 
present as salts of carbonic acid. 

Analysis of the data obtained by means of 
radioactive carbon dioxide has shown that 
absorption in living sunflower leaves is ac- 
complished: (1) by solution of the carbon 
dioxide in the water of the sap; (2) by reac- 
tion of the carbon dioxide with buffer sub- 
stances in the sap to form bicarbonate ion; 
and (3) by reaction with insoluble carbonates 
to form bicarbonates soluble in the sap of the 
leaf. From chemical analysis and from the 
variation in the amounts of radioactive carbon 
retained after treatment of the leaves with 



150 



CARNEGIE INSTITUTION OF WASHINGTON 



different partial pressures of carbon dioxide, 
it has been demonstrated satisfactorily that 
the insoluble carbonate participating in the 
absorption is principally calcium carbonate. 

In addition to the three types of absorption 
mentioned, a small amount of radioactive 
carbon dioxide reacted to form organic com- 
pounds. The radioactive carbon so fixed 
amounted to about 3 per cent of the carbon 
absorbed from the surrounding atmosphere. 
The amount fixed did not increase with time, 
after 15 minutes, but did increase with re- 
peated saturation of the leaf with radioactive 
carbon dioxide. Killing the leaf by freezing 
inhibited the reaction. The nature of this 
radioactive organic material is still obscure. 
The formation of this material may be with- 
out significance to the photosynthetic process, 
but the fact that leaves produce organic matter 
from carbon dioxide without exposure to light 
is important in itself. 

The question whether the carbon dioxide 
absorbed by leaves previous to illumination 
can be used in photosynthesis was also investi- 
gated. Leaves were saturated with radioactive 
carbon dioxide and then completely removed 
from the external supply of this gas before 
being illuminated. After illumination the 
leaves were tested for radioactive organic 
material. In every case, such leaves contained 
about 3 to 10 times more radioactive carbon 
than the corresponding unilluminated leaves. 
Leaves were able to photosynthesize this ab- 
sorbed radioactive carbon dioxide for 30 
minutes or more after removal from the ex- 
ternal supply of radioactive gas. The greatest 
amount of utilization occurred when the 
leaves were illuminated immediately after 
saturation. This is not surprising in view of 
the rapid depletion of the internal supply of 
radioactive carbon dioxide owing to its out- 
ward diffusion. From these experiments it 
was concluded that the absorption of carbon 
dioxide for use in the photosynthetic process 
is independent of the photochemical reaction. 

The mechanism whereby the carbon di- 
oxide absorbed by the leaf enters the photo- 
chemical reaction in photosynthesis is quite 
unknown. There is no basis as yet for decid- 
ing whether it enters as free carbon dioxide, 



as bicarbonate ion, or as some organic deriva- 
tive of carbon dioxide. 

The question naturally arises whether the 
compounds newly formed in photosynthesis 
are quickly used in respiration. Leaves which 
had been saturated with radioactive carbon 
dioxide were illuminated so as to form radio- 
active organic material. Immediately after 
illumination these leaves were placed in the 
dark and the rate of loss of radioactive organic 
carbon was followed. By this method it was 
clearly demonstrated that the compounds pro- 
duced in photosynthesis disappeared quite 
rapidly. It still remains to be determined 
how this rate compares with the rate of respi- 
ration of known compounds such as glucose. 

The radioactive carbon used in these experi- 
ments was prepared by bombardment of 
boron oxide with 2MEV deuterons. About 
60 per cent of the radioactive carbon con- 
tained in the target at the end of the bombard- 
ment was recovered in the form of radio- 
active carbon dioxide. This radioactive gas 
was diluted about io 14 times with ordinary 
carbon dioxide to make it suitable for use. 
A method was developed for the quantitative 
determination of the radioactivities of the 
various samples encountered in this investiga- 
tion. The apparatus consisted of a Lutz- 
Edelmann electrometer connected to an ion- 
ization chamber, under which the sample to 
be measured was placed in a specified posi- 
tion. Samples of radioactive carbon dioxide 
were dissolved in potassium hydroxide solu- 
tion prior to measurement. The radioactive 
decay of the various samples was corrected 
for by means of the half-life constant of C 11 , 
20.35 rninutes. This value was determined 
as the average of several measurements and 
is probably accurate to ±0.08 minute. 

Unilluminated nettle leaves, like sunflower 
leaves, absorb relatively large quantities of 
carbon dioxide. For this reason a comparison 
of the two absorption systems has been under- 
taken. The results obtained thus far indicate 
that the two systems are similar: that in both, 
carbon dioxide is absorbed by the water of 
the leaf, by buffers contained within the sap 
of the leaf, and by insoluble carbonates. 



DIVISION OF PLANT BIOLOGY 



151 



Oxidation-Reduction Reactions in 
Killed Leaves 

Investigations of the labile chemical systems 
that are believed to form a part of the photo- 
synthetic mechanism of green plants have 
revealed a complex interrelation among many 
reactions. This is particularly true of the 
oxidative processes that occur when leaves 
are killed under conditions that are not 
destructive to enzymes. 

If leaves of young plants or of etiolated 
seedlings are killed with anesthetics, by grind- 
ing, or by freezing and thawing, a great many 
of the constituents of the plastids, such as 
ascorbic acid and the carotenoid pigments, 
are destroyed through oxidation. In the case 
of clover leaves, a portion of the oxidized 
ascorbic acid is reduced again when the killed 
leaves are placed in vacuum. With leaves of 
several other plants tested, only traces of 
ascorbic acid are regenerated in the absence 
of oxygen. In all these plants, carotenoids 
destroyed through oxidation are not re-formed 
in vacuum or in the presence of ascorbic acid. 
An excess of ascorbic acid does not reduce 
the carotenoids contained in living or in 
killed sections of carrots and of etiolated 
leaves. 

Oxidation of ascorbic acid in killed leaves 
appears to be catalyzed by an enzyme, the 
nature of which has not been determined. 
This enzyme system is not expressable with 
the juice from whole killed leaves, and it is 
not extractable with water from freshly 
ground barley leaves. The capacity of killed 
leaves to oxidize ascorbic acid is destroyed by 
cyanides and by strong solutions of urea. It 
is not altered by dilute solutions of urea or 
glycerine. Enzyme inactivated by urea or 
cyanide is not restored through removal of 
these compounds by dialysis. Although the 
ascorbic acid oxidase system is very resistant 
to drying, it is rapidly inactivated when fresh 
leaves are heated. 

In last year's report, it was pointed out that 
the oxidation of carotenoid pigments in killed 
leaves is apparently dependent upon oxidation 
of ascorbic acid or other compounds. It has 
since been found that in some plant materials 



oxidation of carotenoids is coupled with an 
oxidation of unsaturated fats. 

Other investigators have found in soy beans 
an enzyme that accelerates the addition of 
atmospheric oxygen to carotenoid pigments 
dissolved in unsaturated fats. Extracts of 
white lupine seeds have also been found to 
increase the oxidation rate of several fats. 
Further investigation of these reactions has 
now demonstrated that this enzyme, which 
occurs in both the green and the mature 
seeds of most legumes, is a highly specific 
catalyst for the addition of oxygen to 
certain unsaturated fats and fatty acids. 
Only those compounds that contain the 

H H 
— C = C(CH 2 ) 7 C(0) — group are attacked 
by the enzyme and oxygen. Such compounds 
were either oleic, ricinoleic, eleostearic, lino- 
leic, and linolenic acids or their esters or 
amides. Compounds with even minor struc- 
tural differences, as elaidic acid, the trans- 
isomer of oleic acid, oleyl alcohol, the reduced 
carboxyl derivative of oleic acid, and erucic 
acid, with 11 instead of the usual 7 carbon 
atoms between the ethylene group and the 
carboxyl group, were not oxidized. However, 
these three compounds did not prevent the 
addition of oxygen to oleic acid by the 
enzyme. 

Study of the oxidation of carotenoid pig- 
ments by the enzyme from legumes revealed 
that these pigments are not oxidized directly. 
The reaction depends upon simultaneous oxi- 
dation of the unsaturated fats. Carotenoids 
dissolved in saturated fats or in unsaturated 
compounds that are not oxidized by the en- 
zyme are also unattacked by the enzyme and 
oxygen. Carotenoids, dissolved in unsaturated 
fats that had been partially oxidized but from 
which the enzyme had been removed, were 
not oxidized. 

Substances other than the carotenoids are 
also oxidized when dissolved in unsaturated 
fats and treated with the enzyme from 
legumes. Of special interest in this connec- 
tion is the oxidation of the green chlorophylls 
to colorless products. 

The rate of oxidation of carotenoids by the 
legume enzyme and unsaturated fats depends 



152 



CARNEGIE INSTITUTION OF WASHINGTON 



upon the autoxidizability of the pigments 
themselves. Zeaxanthin, the most stable of 
the leaf xanthophylls, is oxidized more slowly 
than the other leaf carotenoids. Eschscholtz- 
xanthin, the least stable of the known xan- 
thophylls, is oxidized most rapidly. 

Thus far it has been impossible to prove 
that leaves contain the same oxidative enzyme 
found in seeds of legumes. It is of signifi- 
cance, however, that, in many respects, the 
oxidative properties of killed leaves resemble 
those of the legume seeds. Extracts of older 
green leaves inhibit oxidation of fats and dis- 
solved carotenoids by the enzyme from 
legumes. This inhibition of the oxidation of 
the yellow pigments is similar to that ob- 
served in leaves themselves several years ago. 

Preparation from plants of an enzyme that 
catalyzes addition of oxygen to the carbon 
atoms of double bonds throws a new light on 
the mechanism of respiration or oxidative 
metabolism. It now appears that respiration 
may involve direct addition of oxygen to car- 
bon atoms as well as oxidation through re- 
moval of hydrogen by so-called hydrogen 
carriers or acceptors. 

Oxidation of the carotenoids by the enzyme 
from legumes and by leaves depends upon the 
state or physical condition of the pigments. 
For example, if carotenoids are dispersed as 
a colloidal solution in water before treatment 
with enzyme and fat, little or no oxidation 
of the pigments takes place. These results as 
well as observations recorded in the follow- 
ing section of this report point to the impor- 
tance of knowledge concerning the state and 
distribution of pigments in leaves to an inter- 
pretation of their function. 

Destruction through oxidation of the tan- 
nins contained in some leaves presents many 
baffling problems. The enzyme system most 
likely to catalyze oxidation of these com- 
pounds is cytochrome and its oxidase. As yet, 
the usual spectrometric methods for detection 
of reduced cytochrome have failed to reveal 
its presence in these leaves. Whether or not 
all leaves contain this or another similar 
system remains to be established. 

When leaves are killed in the presence of 



thiobarbituric acid and air, there is formed a 
red compound that exhibits selective absorp- 
tion of light of wave length 531 m\i. This 
same colored compound may be formed by 
treating a number of compounds of diverse 
chemical structures with hydrogen peroxide 
for several days, then adding thiobarbituric 
acid after the excess of hydrogen peroxide has 
been decomposed with manganese dioxide. 
Presumably the formation of the colored com- 
pound in plants follows an analogous course. 

The State of Pigments in Leaves 

Yellow and green pigments as they are 
found in leaves and in extracts formed by 
grinding leaves with water exhibit spectral 
absorption properties that are slightly differ- 
ent from those of the same pigments dissolved 
in the common organic solvents. In the aque- 
ous extracts, the pigments appear to be asso- 
ciated with protein, and as a consequence, it 
has been assumed that the unique spectral 
properties of the pigments in the leaf are the 
result of a chemical union between the pro- 
tein and the pigments. 

Investigations carried on during the past 
year have shown, however, that it is possible 
to prepare dispersions of chlorophyll in water 
which exhibit all the spectral properties dis- 
played by chlorophyll in the leaf, without a 
trace of protein present. If a protein, like 
albumen, is added to such a chlorophyll prep- 
aration, the pigment particles associate them- 
selves with the protein particles and can be 
precipitated with them, but there is no fur- 
ther change in the spectral properties of the 
mixture. If tannic acid is added to these 
protein-colloidal chlorophyll mixtures, the pig- 
ment is precipitated with the protein. A 
similar phenomenon is encountered in grind- 
ing leaves that contain tannins. As yet it is 
not known whether the mixtures of pigments 
and proteins obtained by grinding leaves are 
normal constituents of the living leaf or are 
artifacts. Information obtained so far does 
not support the postulations that, in the leaf, 
chlorophyll is associated in large units con- 
taining as many as 3000 molecules, and that 
all these molecules are associated with protein. 



DIVISION OF PLANT BIOLOGY 



153 



The Origin of Hexenaldehyde Obtained 
from Leaves 

It has been known for some years that 
many species of leaves yield hexenaldehyde, 
hexen-(2)-al(i), up to 0.02 per cent of the 
fresh weight of the leaves. Some years ago 
histological evidence was advanced to the 
effect that the aldehyde was localized in or 
about the chloroplasts. This, together with 
the fact that the content of hexenaldehyde in 
leaves seemed to be influenced positively by 
illumination, and the obvious similarity in 
chemical structure between hexenaldehyde 
and the hexose sugars, served to build a 
hypothesis that this aldehyde represented the 
first or an early step in the photosynthetic 
process. An investigation has been carried 
out by Mr. William Nye to determine the 
role, if any, that this leaf aldehyde plays in 
photosynthesis. 

The experiments demonstrate that the 
amount of hexenaldehyde obtained from 
leaves is influenced more by factors involved 
in the isolation process than by the periods 
of illumination or darkness to which the 
leaves are exposed. The isolation procedure 
consists of steam distillation of ground leaf 
material, and the precipitation of the hexen- 
aldehyde in the distillate by means of 3-nitro- 
benzhydrazide. The experimental evidence 
now obtained points to the conclusion that 
the aldehyde is formed during the process of 
grinding. Leaves which had been killed with 
hot water, toluene, or chloroform before 
grinding yielded little or no aldehyde, nor 
was aldehyde obtained by the distillation of 
whole leaves. 

When leaves are ground in a ball mill in 
an atmosphere of air or oxygen, there is a 
decrease in pressure in the ball mill, and the 
aldehyde can be obtained upon distillation of 
the ground mass with steam. When, on the 
other hand, leaves are ground in an inert 
atmosphere such as nitrogen or carbon di- 
oxide, the pressure remains the same, or in- 
creases, and no aldehyde is obtained on distil- 
lation. The influence of grinding on the 
production of the aldehyde was demonstrated 
in a number of ways. It is primarily the 



grinding of the living leaf tissue in contact 
with oxygen which is responsible for the pro- 
duction of the aldehyde. For example, much 
more aldehyde is obtained from leaves ground 
in nitrogen, cold water added, then ground in 
oxygen and distilled, than from leaves ground 
in nitrogen, boiling water added, then ground 
in oxygen and distilled. 

The experiments also demonstrate that 
the leaf aldehyde is, for the most part, a result 
of injury in the presence of oxygen, and that 
it is formed by some enzymatic oxidation 
process. In an effort to determine the sub- 
strate which is oxidized, small amounts of 
ethyl, n-butyl, n-hexyl, and benzyl alcohols 
were added to leaves before grinding. None 
of these alcohols gave evidence of being oxi- 
dized to the corresponding aldehydes by this 
system. The yield of hexenaldehyde was in- 
creased by the addition of oleic acid and of 
benzyl alcohol, and this is due apparently to 
the presence of peroxides in these substances. 
That a type of coupled oxidation may be in- 
volved in the formation of the hexenaldehyde 
is indicated by the fact that antioxidants such 
as pyrogallol distinctly inhibit the formation 
of the aldehyde. Ten different species of 
leaves were examined in this investigation. 
The leaves of Atlanthus glandulosa proved 
to be the most satisfactory, because its long 
compound leaves permitted the preparation 
of large duplicate samples by the half-leaf 
method. 

In order to confirm the chemical structure 
which has been ascribed to the leaf aldehyde 
obtained from these plants, hexene-(2)-al-(i) 
was synthesized in the laboratory. This alde- 
hyde formed a m-nitrobenzhydrazide which 
was identical with that obtained from the leaf 
aldehyde. It is highly probable that the leaf 
aldehyde represents an intermediate oxidation 
product, resulting from enzymatic oxidation 
of the corresponding hexene alcohol. This 
oxidation may be carried beyond the aldehyde 
stage if the ground fresh leaf material is per- 
mitted to remain in contact with air for longer 
periods of time. It is highly probable that this 
accounts for the variable yields of hexenalde- 
hyde which were obtained, as the aldehyde 



154 



CARNEGIE INSTITUTION OF WASHINGTON 



must thus be considered an intermediate 
product of the oxidation of the alcohol to the 
corresponding acid. 

The results from this investigation consti- 
tute further evidence of the great lability of 
many of the constituents of living cells, and 
of the ease with which these constituents 
undergo oxidative change when the cells are 
killed. Conclusions concerning the chemistry 
of organisms can for the most part be drawn 
only from data of chemical analysis of such 



organisms or of particular tissues. Yet such 
analyses usually involve the killing of the 
cells. As has been pointed out in previous 
reports, many cell constituents undergo drastic 
changes the moment the cells are killed. This 
leads to the destruction of many physiologi- 
cally important constituents, and, as in the 
case just discussed, to the formation of sub- 
stances which are not constituents of the 
living organism or are contained therein in 
only very small amounts. 



THE QUANTUM EFFICIENCY OF PHOTOSYNTHESIS 

Robert Emerson and Charlton M. Lewis 



It was stated in last year's report that the 
high photosynthetic efficiencies found by War- 
burg and Negelein, and confirmed by Rieke, 
were dependent on a certain combination of 
conditions of culturing the cells and carrying 
out the measurements of photosynthesis. Still 
higher efficiencies were obtained by further 
adjustment of conditions. The highest values 
verged upon being inconsistent with thermo- 
dynamic requirements. There were other 
reasons as well for questioning the reliability 
of certain of the assumptions upon which the 
computed efficiencies were based. These as- 
sumptions related to the measurement and 
calculation of the rate of photosynthesis. The 
procedure of Warburg and Negelein had been 
followed because the initial objective was the 
confirmation or rejection of their results. 
These workers assumed that for each mol of 
oxygen produced by assimilating cells, one 
mol of carbon dioxide was absorbed. Several 
tests of this assumption were made during 
the fall of 1939. The results showed that dur- 
ing prolonged periods of light or darkness 
the ratio of exchange of oxygen and carbon 
dioxide may approach a value close to unity, 
but that during the short periods of light and 
darkness used for measuring efficiency this 
ratio may be far from unity, and may be 
subject to sudden fluctuations. During the 
first moments of illumination following a 
dark period, there is regularly less carbon 
dioxide absorbed than oxygen produced. 
With light intensities slightly higher than 



those customarily used for measuring effi- 
ciency, the deficit in absorption of carbon 
dioxide becomes a positive evolution of carbon 
dioxide. During the dark period following a 
light exposure, when respiration is meas- 
ured, less carbon dioxide is produced than 
the amount of oxygen consumed. Thus one 
of the fundamental assumptions upon which 
the photosynthesis measurements had been 
based proved to be incorrect. When photo- 
synthesis is calculated from observed pres- 
sure changes on the basis of an assumed 
equality of exchange of oxygen and carbon 
dioxide, the changing ratio of exchange re- 
sults in a computed rate of photosynthesis 
considerably higher than the true rate. The 
very high efficiencies reported last year re- 
sulted from this misinterpretation of the 
measurements. 

Though it is not possible to state with cer- 
tainty that Warburg and Negelein's efficien- 
cies were subject to the same error, neverthe- 
less a number of details of their observations 
are in such close agreement with our own, 
and are so readily interpreted on this basis, 
that it seems more than likely that their high 
efficiencies resulted from the same misinter- 
pretation of data. In the case of Rieke's 
measurements, data are included which make 
a more direct comparison with our own re- 
sults possible. Here it is clear that his high 
efficiencies resulted from the same error 
which was involved in our own. 

Before reporting further work on the quan- 



DIVISION OF PLANT BIOLOGY 



155 



turn efficiency, it is appropriate to mention 
some of our observations on the carbon 
dioxide exchange which proved so disturbing 
to the earlier efficiency measurements. The 
cells appear to contain a system which ex- 
changes carbon dioxide in a manner not re- 
concilable with the usual concept of respira- 
tion and photosynthesis. Though this system 
may play no direct part in either respiration 
or photosynthesis, its potential importance 
for plant physiology should not be overlooked. 
It may also prove to be related to other 
aspects of carbon dioxide absorption by leaves 
being investigated in this Division. 

The irregularities in the carbon dioxide 
exchange in both light and darkness are de- 
pendent on the continued physiological ac- 
tivity of the cells. Boiled cells do not show 
these responses. Concentrations of phenyl 
urethane sufficient to inhibit photosynthesis 
also inhibit carbon dioxide evolution in re- 
sponse to illumination. This carbon dioxide 
evolution seems to depend on oxygen respira- 
tion during the preceding dark period. If 
only a limited amount of oxygen has been 
available, so that it is quickly consumed in 
the dark and aerobic respiration ceases, then 
there will be a correspondingly limited pro- 
duction of carbon dioxide upon illumination. 
If no oxygen is available during the dark 
period, then illumination will produce no 
carbon dioxide. Respiration in the dark must 
continue for a period of about one hour in 
order to produce a maximum evolution of 
carbon dioxide in a subsequent light exposure. 
If the dark period follows an exposure to 
strong light, the carbon dioxide production is 
at first much less than the consumption of 
oxygen in respiration, but gradually increases 
until the two become nearly equal. Up to 
this time there has been a deficit of carbon 
dioxide production, the magnitude of which 
can be calculated on the assumption that 
oxygen and carbon dioxide are exchanged in 
equal amounts in the respiratory process, and 
that the carbon dioxide which failed to ap- 
pear was stored in some reservoir inside the 
cells. Now when the light is turned on, oxy- 
gen consumption due to respiration gives way 



to oxygen production due to photosynthesis, 
and at the same time there is a great increase 
in carbon dioxide production, as if the reser- 
voir filled during the dark period were sud- 
denly being emptied. This unexpected carbon 
dioxide production gives way after a few 
minutes to a small but slowly increasing car- 
bon dioxide absorption, which in time be- 
comes equal to the oxygen production. There 
has now been a net deficit of carbon dioxide 
absorption, and its size may be calculated on 
the same assumption made for the dark 
period, namely, that oxygen and carbon di- 
oxide have really been exchanged in equal 
amounts, this time in photosynthesis instead 
of respiration, and that the deficit in carbon 
dioxide absorption is due to the emptying of 
the reservoir which was slowly filled during 
the preceding dark period. Both of these 
calculations are necessarily inexact because 
the return to equality of gas exchange in both 
light and darkness is approached asymptoti- 
cally. But the agreement of the figures for 
carbon dioxide absorption in darkness and 
evolution in light lends support to the assump- 
tions made, and to the idea of a reservoir. 
The emptying of the reservoir in the light 
causes a much more striking disturbance in 
pressure change than its filling in the dark, 
because the former is nearly completed dur- 
ing the first two minutes of illumination. 
The filling in the dark starts less rapidly, and 
does not exceed the rate of carbon dioxide 
production due to respiration. There is no 
sudden reduction of pressure in the dark 
comparable with the burst of pressure on 
illumination. 

If the carbon dioxide reservoir has been 
filled during a long period of darkness, the 
degree to which it can be emptied by light 
depends on the intensity used. If a low in- 
tensity is used first, and the reservoir partially 
emptied, then a higher intensity will produce 
a further evolution of carbon dioxide, up to 
the point where the reservoir is completely 
emptied. There is evidence that this is accom- 
plished with light intensities far below that 
required to saturate photosynthesis. This 
may be one reason why the phenomenon has 



156 



CARNEGIE INSTITUTION OF WASHINGTON 



generally been overlooked. In experiments on 
the maximum rate of photosynthesis, the 
photosynthesis itself is so rapid as to obscure 
the existence of the reservoir. But maximum 
efficiency of photosynthesis prevails at slower 
rates, and at light intensities where the 
reservoir plays a prominent part in the gas 
exchange. 

The experiments reported here were done 
with sodium light. There is evidence that the 
wave length, as well as the light intensity, 
may be a determining factor in the emptying 
of the reservoir. 

The amount of carbon dioxide absorbed in 
the dark, and the amount produced in light 
of optimum intensity, depend on the partial 
pressure. At the carbon dioxide concentra- 
tion of ordinary air, the existence of the 
reservoir is scarcely detectable. It becomes 
noticeable, though still very small, at about 
0.5 per cent carbon dioxide. At 5 per cent, 
the concentration formerly used for efficiency 
measurements, the filling and emptying of 
the reservoir are prominent, and cause rates 
of pressure change more rapid than those 
caused by respiration. The effects are some- 
what larger at 12 per cent. 

These pressure disturbances can result in 
errors in the photosynthesis measurements in 
two ways. Both their magnitude and their 
distribution in time can play important parts. 
A number of factors were formerly found to 
be significant in producing high efficiencies 
by the method of Warburg and Negelein, but 
have since been shown to play no part in the 
efficiency as determined by present methods. 
It may be inferred that such factors increased 
the prominence of the pressure changes caused 
by the carbon dioxide reservoir, but separate 
experiments to show whether the effect was 
due to the size of the pressures or to their 
distribution in time have not been made. 
Factors in this class are the temperature of 
measurement, io° C. giving maximum effect; 
an abundance of microelements in the culture 
medium; and a low light intensity for cultur- 
ing the cells, combined with a reduction in 
intensity shortly before harvesting the cells. 

To avoid errors introduced by the carbon 
dioxide reservoir, oxygen exchange alone has 



been used as a measure of photosynthesis. 
Efficiency measurements are now made with 
cells suspended in a carbonate-bicarbonate 
buffer mixture which maintains a constant 
partial pressure of carbon dioxide. The rate 
of oxygen exchange comes quickly to equi- 
librium after each change of conditions, and 
the computed rate of photosynthesis is inde- 
pendent of the time periods chosen for light 
and darkness. Assuming that oxygen produc- 
tion is a measure of carbohydrate synthesis 
from carbonic acid, the maximum efficiency 
of Chlorella pyrenoidosa in the region of the 
yellow sodium line is about 25 per cent, in- 
stead of about 50 per cent as reported by 
Warburg and Negelein. 

The measurements will gain much in sig- 
nificance if a given efficiency can be shown 
to be characteristic of the photosynthetic proc- 
ess in general, rather than being limited to 
a relatively unimportant organism which 
happens to be suited to the precise methods 
required for efficiency measurements. The 
accompanying table shows that values in close 

Quantum yield at 
Organism about 1200 

ergs/cm. 2 /sec. 

Chlorella pyrenoidosa 0.101 

Chlorella vulgaris 0.092 

Chlorococcus sp 0.104 

Eudorina sp 0.095 

Stichococcus bacillaris 0.107 

Scenedesmus D 1 0.094 

Scenedesmus D 3 0.100 

Gyormana humicola 0.090 

Oocystis naegeli 0.096 

Chroococcus sp c.086 

Wolffiella lingulata 0.060 

agreement have been obtained for a fairly 
diverse group of organisms. Efficiencies are 
expressed as quantum yields, the significance 
of which is discussed below. Seven of the 
values fall within a range of about 10 per 
cent, and the others are not far off. Nine 
different species of green algae are included, 
as well as one blue-green alga, a species of 
Chroococcus. This is a member of the Myxo- 
phyceae, probably related to the molds, and 
perhaps representing a more primitive type 
of alga. It has the additional interest of a 
very different pigment complex. A tentative 



DIVISION OF PLANT BIOLOGY 



157 



value is also included for the small aquatic 
flowering plant Wolffiella. Our method of 
measurement is not as well adapted to the 
study of this organism as it is to the algae, 
and the efficiency figure lacks precision. It is 
nevertheless interesting that a flowering plant 
can show a photosynthetic efficiency of the 
same order of magnitude as those of the vari- 
ous algae studied. The collected results sug- 
gest that the efficiency measurements made 
with Chlorella may become a basis for more 
general considerations concerning the nature 
of the photosynthetic process. 

The efficiency of Chlorella pyrenoidosa has 
been studied in more detail, and every effort 
has been made to find conditions which 
would lead to higher values. But the maxi- 
mum efficiency seems to be far less dependent 
upon cultural and experimental conditions 
than had previously been supposed. Factors 
mentioned last year as influencing the effi- 
ciency measured by the method of Warburg 
and Negelein are largely without effect on the 
efficiency measured by oxygen production. 
Cells may be grown over a wide range of 
light intensities, and show the same efficiency. 
The age of the culture is of no importance 
within wide limits, provided an abundance 
of microelements is present initially. Shortage 
of microelements in the culture medium re- 
sults in diminished efficiency. In maintaining 
or restoring the maximum value, the element 
manganese plays a major part. Under some 
circumstances it may have an effect within a 
short period after it is supplied. 

The efficiency is relatively independent of 
the temperature. Measurements made at o°, 
io°, and 20 C. give values in close agree- 
ment. This is of particular interest because 
of the great difference in rate of respiration 
over this range of temperatures. The respi- 
ration enters as a correction to every photo- 
synthesis measurement. As yet there is no 
method of measuring respiration simultane- 
ously with photosynthesis, so the rate is meas- 
ured immediately before and after each light 
exposure. It is assumed that this rate is a 
close approximation to the rate prevailing 
during the light exposure. Were this not so, 
one would hardly expect such close agree- 



ment in efficiency over a temperature range 
from o° to 20 . 

Respiration may be varied in other ways 
without altering the efficiency. Cells grown 
at high light intensity may have a rate of 
respiration 2 or 3 times that of cells grown 
at a lower intensity, and yet show the same 
quantum yield. 

An efficiency of 25 per cent in sodium light 
is equivalent to a quantum yield of about 
0.12, or a quantum number of about 8 (see 
accompanying table). This is in good agree- 

Different ways of expressing efficiency 



Per cent Cfor 






sodium light, 


Quantum 


Quantum 


V = 589 mm.) 


yield 


number 


28.5 


0.125 


8 


25.4 


O.III 


9 


22.8 


O.I 00 


10 


20.8 


0.091 


11 


19.0 


0.083 


12 


17.6 


0.077 


13 


16.3 


0.072 


14 


15.2 


0.067 


15 



ment with results obtained by the group 
working on photosynthesis at the University 
of Wisconsin, where several other methods 
of measurement have been used. A quantum 
number of 8 means that eight quanta must 
be absorbed for each molecule of oxygen pro- 
duced in photosynthesis, and presumably for 
each carbon dioxide molecule reduced to car- 
bohydrate. Whereas Warburg and Negelein's 
quantum number of 4 indicated an astonish- 
ing efficiency, quite out of line with that of 
other physiological processes, 8 provides suffi- 
cient energy so that photosynthesis becomes 
more readily conceivable in terms of the 
known principles of chemical thermodynam- 
ics. But the rejection of the number 4 in favor 
of a higher figure reduces the value of specu- 
lation as to the sequence of chemical steps 
by which the plant produces carbohydrate 
from carbonic acid. If the quantum number 
is used as a guide to the number of photo- 
chemical steps involved, a value of 8 permits 
so many different reaction combinations as 
to render speculation along these lines almost 
fruitless at the present stage of knowledge. 



i 5 8 



CARNEGIE INSTITUTION OF WASHINGTON 



Having rejected Warburg and Negelein's 
value for photosynthetic efficiency because of 
the method of measurement, we must also 
question their results on the dependence of 
efficiency upon wave length. It is therefore 
more than ever essential to carry out effi- 
ciency measurements at different wave 
lengths, using improved methods. During 



the past year, good progress has been made 
on the construction of a monochromator for 
this purpose. Generous cooperation has been 
received from members of the staff of the 
Mount Wilson Observatory. It is hoped that 
the rest of this year will be devoted largely 
to a study of the dependence of efficiency on 
wave length. 



INVESTIGATIONS ON THE CAMBIUM AND ITS DERIVATIVE TISSUES 

/. W. Bailey 



The major objectives of these investigations 
and their significance in the consideration of 
certain physiological, biochemical, and bio- 
physical problems have been outlined in pre- 
vious Year Books, Nos. 32 to 38. There are 
other aspects of the work which bear upon 
problems in the fields of taxonomy and paleo- 
botany. Extensive investigations of the stems 
of a wide range of representative angiosperms 
have demonstrated statistically that there are 
clearly defined trends of structural specializa- 
tion in the conducting tissues of the xylem. 
Certain of these trends of evolutionary modi- 
fication are irreversible and are more or 
less closely synchronized with concomitant 
changes in the storage parenchyma and 



cambium. They are, therefore, significant in 
any general discussion of the phylogeny, rela- 
tionships, and classification of the angio- 
sperms. It has seemed advisable in this con- 
nection to institute an intensive study of some 
particular family of the dicotyledons and to 
determine to what extent the structural modi- 
fications of the cauline cambium and xylem 
are correlated with evolutionary specializa- 
tions in other organs and tissues. During the 
past year, therefore, attention has been fo- 
cused upon the task of assembling adequate 
material of the pantropical family Icacinaceae 
as a basis for such an investigation, and of 
preparing stems, nodes, leaves, flowers, and 
pollen for detailed microscopic investigation. 



EXPERIMENTAL TAXONOMY 
Jens Clausen, David D. Kec\, and William M. Hiesey 



The investigations in this field, dealing 
with the forces that govern the appearance, 
distribution, and evolution of plants under 
natural conditions, are progressing along 
several fronts. The governing factors are 
closely interwoven and must be considered 
together. Such investigations must also em- 
ploy various groups of plants, for life exists 
in so many patterns that a one-sided approach 
is apt to result in incomplete or even mislead- 
ing interpretations. Practical considerations, 
however, make it imperative to concentrate 
effort on problems of highest strategic impor- 
tance, advancing first in one direction, then 
in another, according to a predetermined 
plan, and finally coordinating the results. 



During the current year, attention has 
again been turned toward a study of the 
genetic systems which characterize species 
and their regional races. This has followed 
a period of concentrated study on the eco- 
logical differentiation in complexes of peren- 
nial species as expressed in the reactions of 
their component races to contrasting environ- 
ments (see Carnegie Institution of Washing- 
ton Publication No. 520, Experimental studies 
on the nature of species. I. Effect of varied 
environments on western North American 
plants). 

Our studies on the genetic basis of species 
have focused mainly on the annual tarweeds 
(Madiinae). Work on these plants was begun 



DIVISION OF PLANT BIOLOGY 



159 



from a taxonomic viewpoint by the late Dr. 
H. M. Hall, and entered its genetic phase in 
1932. Members of this subtribe of Com- 
positae have proved to be particularly desir- 
able subjects for experimental study because 
they show an exceptionally complete array of 
relationships and a great variety of evolu- 
tionary patterns. So much information has 
been obtained on the general problem of the 
nature of species from the Madiinae as a 
whole that it was found desirable to concen- 
trate the experimental work during 1940 on 
Layia and Madia. The account of these 
genera will be brought to publication as soon 
as the data on hand have been fully analyzed. 
Then the garden studies on Hemizonia, 
Holocarpha, and Calycadenia, already far ad- 
vanced, will be completed and a companion 
account published. 

The Organization of Plant Groups 

On the background of the best set of data 
on Layia and Madia so far obtained, together 
with those from previous years, we can now 
visualize with increasing clarity the composi- 
tion and interrelations of species in these 
genera. Nearly every one of the more widely 
distributed species is composed of large num- 
bers of local populations. These are geo- 
graphically discontinuous, often separated by 
many miles, and there is slight chance for 
interbreeding between them. Within the 
population, however, there is free interbreed- 
ing. Accordingly, each population, in spite 
of considerable individual variation within 
it, has developed into a morphological-geo- 
graphical unit more or less distinguishable 
from the others. Such local populations, 
therefore, often satisfy the morphological and 
geographical requirements for specific distinc- 
tion, but they fail to satisfy the genetic re- 
quirement, because they interbreed freely 
when given a chance. They represent very 
early stages of differentiation within species 
and are of interest to students of evolution, 
but have no taxonomic standing. 

Of different rank are the regional race 
complexes, or ecotypes, developed in certain 
climates. For example, wherever Layia platy- 



glossa touches the coast, late-flowering races 
have evolved with succulent herbage, short, 
prostrate stems, and thirteen rather than 
eight ray florets. These characteristics are 
heritable, and the prostrate habit may even 
become accentuated in the experiment garden, 
where competition is eliminated. Unrelated 
species have developed strikingly parallel 
races in the maritime environment. The 
maritime populations of a species can be 
recognized as composing a maritime ecotype 
because of their similarity in certain char- 
acteristics. In other characteristics, however, 
the maritime vary as much as the inland 
populations. The characters that vary are pre- 
sumably of no importance for survival in the 
maritime environment. 

A different sort of ecotype has evolved in 
genera that have forms which flower in dif- 
ferent seasons. Such are the spring-flowering 
and fall-flowering ecotypes of species like 
Madia elegans, the M. sativa complex, Hemi- 
zonia luzulaejolia and H. multicaulis of 
Euhemizonia, and one of the Holocarpha 
species. In general the spring-flowering or 
vernal ecotypes are shorter, less glandular, 
and branched farther down, and have dif- 
ferent kinds of leaves from the autumnal 
ecotypes of the same species. They finish 
flowering before the fall ecotypes commence 
to bloom. The two may grow close together 
in the wild, but because of their separation 
in time of development they have very little 
opportunity for crossing under natural condi- 
tions. Their artificial hybrids are fertile, how- 
ever, and the vigorous second generation 
shows a remarkable recombination of parental 
characters in earliness and habit. 

The Madiinae occupy mainly the zones 
from the coast to the Sierran foothills. As a 
consequence they have developed but few eco- 
types. In contrast, most of the perennial 
species complexes employed in the transplant 
investigations extend from the coast to the 
rugged alpine regions of the Sierras and even 
eastward into the arid Great Basin, with an 
increase in the number of ecotypes corre- 
sponding to the number of major climatic 
zones they occupy. 

Without exception it has been found that 



i6o 



CARNEGIE INSTITUTION OF WASHINGTON 



differences between ecotypes depend upon 
series of genes affecting each character, rather 
than upon single pairs of genes. This raises 
a question in regard to the maritime ecotypes: 
Did these originate only once, subsequently 
spreading along the coast, or did their dis- 
connected populations along this narrow belt 
arise independently, each from the nearest 
inland race? 

In order to throw light on this question, 
two races of the maritime ecotype of Layia 
platyglossa were crossed. These races are 
separated in nature by a distance of 150 miles, 
one north of, the other south of San Francisco 
Bay. It was found that all of some 2500 
second-generation offspring were distinctly 
maritime, that is, late and prostrate, with 
short internodes and thirteen rays. This lack 
of segregation indicates that the genes re- 
sponsible for the maritime characteristics were 
identical in the parents and located in 
homologous chromosomes. Otherwise, early 
or erect types should have been segregated. 
This result can be explained most simply by 
assuming that the two races are of the same 
origin and have crossed the barrier of the 
Golden Gate, rather than that long series of 
identical mutations occurred in different 
localities. 

In the Madiinae, then, the more widespread 
species consist of many intermittent and vari- 
able populations, each composed of many bio- 
types or individual variants. The populations 
within major climatic regions tend to form 
complexes of characteristic reaction and ap- 
pearance, the ecotypes. But the genes that 
determine the great morphological and physi- 
ological variation within populations and eco- 
types of one species are of such a nature and 
so arranged that they can be freely inter- 
changed without detriment to the offspring. 

Considerable time was spent in investigat- 
ing the genetic barriers between approxi- 
mately twenty-five species. There are all kinds 
and grades of barriers, delimiting species in all 
stages of differentiation and evolution, as one 
would expect in a dynamic, changing world. 
Any one of many evolutionary avenues may 
lead to effective genetic separation of species, 



but not all result in equal morphological 
distinctness. 

Layia and the sections Euhemizonia and 
Centromadia of Hemizonia are characterized 
by species complexes consisting of genetically 
closely related, although morphologically and 
ecologically quite distinct, species. These 
differ by many genes, but their hybrids are 
relatively fertile (2 to 20 per cent). Madia, 
Calycadenia, and the section Deinandra of 
Hemizonia, on the other hand, consist mainly 
of well isolated single species, separated by 
strong sterility barriers. 

Within Madia two complex groups have 
received special study. One is the 8-chromo- 
some Madia elegans, composed of three or 
four major ecotypes, each consisting of many 
variable populations. From new evidence it 
appears possible that Madia Wheeleri is only 
an ecotype of Madia elegans, although prior 
to these investigations it was considered to 
belong in the genus Hemizonia. The other 
group is the extremely variable, 16-chromo- 
some Madia sativa complex, including M. 
sativa, gracilis, anomala, and capitata, and 
M. chilensis from Chile. Only the last named 
appears separated from the others by a fairly 
strong genetic barrier. The other four are 
composed of many individually distinct but 
variable populations. There are definite 
trends toward the development of geographi- 
cal and seasonal types which are morphologi- 
cally recognizable, but the internal barriers 
separating them appear to be too indistinct to 
warrant their further consideration as species. 
Discovery of imperfect barriers and the occa- 
sional production of spontaneous hybrids in 
this otherwise self-pollinating group makes 
its complexity and the occurrence of many 
intermediate forms more understandable. But 
in this group fairly well-defined ecotypes can 
be recognized, and barriers are developing 
that may lead to future speciation. 

Not only do species differ in size, content, 
and distinctness, but they may either be 
grouped into complexes or be completely iso- 
lated, depending upon the distinctness of the 
barriers between them. So one finds the 
living world to be organized into recognizable 
units of higher and higher order. The organ- 



DIVISION OF PLANT BIOLOGY 



161 



ization is more or less discontinuous, but the 
discontinuities are of different rank. The 
smallest unit above the individual is the popu- 
lation, and the largest unit that one can hope 
to analyze experimentally is the species com- 
plex or cenospecies. 

Madiinae Hybrids 

In addition to the natural races, many 
hybrid combinations of Layia and Madia 
were grown in the Stanford garden in 1940. 
These cultures yielded critical data relating 
to the delimitation of species, to their relation- 
ships, and to their evolutionary background. 
At this time attention is called to only a few 
of the more remarkable hybrids. 

Madia sativa (72 = 16) X Layia platyglossa 
(72 = 7): This was a natural hybrid found 
in a culture grown from seed collected near 
Muir Beach, north of San Francisco. Both 
parental strains from the same locality were 
grown this year, and the hybrid was dis- 
covered in the culture of Madia sativa. It 
increases to three the known intergeneric 
hybrids within the Madiinae (see Year Book 
No. 36 [1936-1937], p. 212). This hybrid, 
although unexpectedly vigorous, is completely 
sterile. It is of special interest because of its 
spontaneous origin. In its natural habitat it 
might well have escaped the notice of 
botanists. 

Crosses of Layia glandulosa, L. gaillardi- 
oides, and L. hieracioides with Layia hetero- 
tricha: These three hybrid combinations are 
of importance because they indicate the re- 
mote relation between L. heterotricha and 
other Layia species. All four species have 
8 pairs of chromosomes. It is very difficult 
to obtain hybrids between L. heterotricha and 
other species of the genus. The first-genera- 
tion hybrids between heterotricha and two 
different strains of glandulosa were decidedly 
weaker than the parents; they were able to 
flower, but were completely sterile. Hybrids 
between heterotricha and gaillardioides de- 
veloped very slowly, and many died as seed- 
lings. The best hybrid produced only an 
unbranched stem 7 cm. tall and bore a single 
head, whereas the parental strains were 50 

14 



cm. tall and 40 cm. broad, and bore 30 to 
100 heads per plant. The other plants of this 
combination died as dwarf seedlings. Evi- 
dently the parental genomes were so unlike 
that the metabolism of even the first-genera- 
tion hybrid was extremely upset. Only one 
plant of heterotricha X hieracioides was ob- 
tained. At first it was vigorous, but later it 
succumbed to a rot in the rosette stage. 

Madia gracilis (72 = 16) X M. citriodora 
(« = 8): This combination has now been 
successfully made, and we hope that in time 
it may produce by amphidiploidy a form 
similar to the new Madia species with 24 
pairs of chromosomes discovered in northern 
California (see Year Book No. 36 [1936— 
1937], p. 211). The hybrid is very slightly 
fertile. 

Production of Amphidiploids 

Two amphidiploid Madiinae have already 
been produced. One is Madia nutans (72 = 9) 
X M. Rammii (72 = 8). This new species has 
become well stabilized in the fourth genera- 
tion; it has 17 pairs of chromosomes, and is 
fertile, true to type, and vigorous. It differs 
in several morphological characters from all 
other species of Madia, and was first men- 
tioned in Year Book No. 35 (1935— 1936), 
p. 212. This artificial new species, produced 
by the addition of all the chromosomes of 
two rather rare species, is now ready to be 
tested for its ability to survive and compete 
under natural conditions. 

The other amphidiploid was produced 
from Layia pentachaeta albida (72 = 8) X 
L. platyglossa (n = y). The parents belong 
in very different cenospecies, difficult to com- 
bine in a cross. In this Fx hybrid some of the 
chromosomes pair occasionally, unlike the 
chromosomes in the Madia amphidiploid just 
mentioned, none of which pair. The new 
amphidiploid has 15 pairs of chromosomes, 
is moderately uniform in garden cultures, and 
differs from both parents and all other species 
of Layia. It appears to be less successful than 
the amphidiploid from Madia nutans x Ram- 
mii, but is more vigorous than the diploid Fi. 
Its branches develop abscission layers next to 
the main stem and tend to drop off. 



1 62 



CARNEGIE INSTITUTION OF WASHINGTON 



Both of these amphidiploids were produced 
in the garden spontaneously from diploid 
gametes, not through the application of arti- 
ficial methods. 

Field Studies 

A trip was made by Drs. Keck and Hiesey 
through the South Coast Ranges of California 
and along the adjoining coast in May to study 
the distribution of the 8- and 16-chromosome 
species previously lumped under Layia hier- 
acioides (see Year Book No. 36 [1936-1937], 
pp. 21 1-2 1 2). Although cytological materials 
taken on the trip still await study, it seems 
clear that the diploid species is confined to 
the area north of Monterey Bay, the tetraploid 
to the area southward and inland in both the 
inner and outer Coast Range. 

Dr. Clausen obtained a series of Achillea 
transplants along the coast from central Cali- 
fornia to southern Oregon. This was aug- 
mented by a series obtained from coastal 
Oregon to central Washington by Dr. Keck. 
A special problem is presented by this genus 
on the Pacific Coast, for in Oregon the hexa- 
ploid species (72 = 27), °f the immediate 
coastal region, is apparently closely pressed 
by the tetraploid (« = i8), of the inlands, 
whereas in central California the tetraploid 
comes no nearer the coast than at mid-eleva- 
tions in the Sierra Nevada. The exact bound- 
aries of these morphologically closely similar 
species and of their ecotypes, and the relation 
between these two species and the rest of the 
A. millefolium complex, remain to be worked 
out as one of the problems continued from 
the transplant experiments. 

Cytological Studies 

Material for cytological study has been pre- 
served from practically all the new strains and 
hybrids grown this year. This amounts to 
approximately 850 fixations in Layia and 
Madia alone. These are to be studied in con- 
junction with material obtained in previous 
years, so that a complete cytological investi- 
gation will have been made. Dr. Hiesey spent 
much of the winter and spring upon the 



cytology of Layia species and hybrids. Dr. 
Keck also has spent considerable time with 
the cytology of Artemisia and Penstemon. 

Chromosome counts have been made on a 
number of species and races in the American 
members of the Artemisia vulgaris complex 
in connection with a taxonomic study. The 
following chromosome numbers are addi- 
tional to the ones reported in Year Book No. 
38 (1938-1939), p. 125: A. Carruthii 
(Kansas to Arizona and Chihuahua), n = g; 
A. serrata (Minnesota to Illinois and Iowa), 
« = i8; and A. longifolia (Saskatchewan and 
Alberta to South Dakota and Wyoming), 
72 = 18. Added to the previous results, this 
indicates that the North American species 
formerly included under the European Arte- 
misia vulgaris constitute an interesting poly- 
ploid complex well adapted to experimental 
studies on evolution. A similar situation may 
obtain in the Artemisia campestris complex, 
where A. campestris from the coast of Den- 
mark is found to have 18 pairs of chromo- 
somes, whereas A. pycnocephala from the 
coast of California, recently treated as a sub- 
species of campestris, has only 9 pairs. 

Selection Experiment 

This experiment has been mentioned in 
previous reports (see Year Book No. 36 
[1936-1937], p. 213, and No. 37 [1937- 
1938], p. 221). Its purpose has been to ex- 
change and recombine the genes distinguish- 
ing the Sierran foothill and alpine ecotypes 
of Potentilla glandulosa, and then to test the 
relative survival and mode of reaction of the 
second-generation offspring of this hybrid 
under three contrasting climates. 

As a result of the gene exchange, an ex- 
tremely variable second generation was pro- 
duced. The range of its variability and reac- 
tions extends beyond that of the parental 
ecotypes. Each of the approximately 600 
plants of this population was divided as a 
clone and set at all three stations in 1938 in 
order that its reactions might be studied and 
compared with those of its parents and of all 
the previous transplants of this species. No 



DIVISION OF PLANT BIOLOGY 



163 



experiment of this nature has ever before 
been performed. 

In the third year of selection on this F 2 it 
is found that the results have not been follow- 
ing a predictable pattern. The survival at 
Timberline is better than would have been 
anticipated from the known behavior of the 
foothill grandparent and the Fi. It is now 
apparent that at least 50 per cent of the plants 
set at Timberline will be able to survive a 
third winter. 

New forms that are unlike any plants 
found in nature have arisen from the cross, 
and some may be even better adapted to con- 
ditions at one station or another than the 
native races found there. A few appear to 
have the capacity to survive at all three sta- 
tions. There are, for instance, plants that in 
their morphological characters are similar to 
the foothill ecotype, and, like it, are tall at 
Mather and Stanford. But they also grow 
taller than the native alpines in the short sum- 
mer at Timberline, and seem to be as early 
and frost-resistant as these. In other words, 
their morphology and size is that of the foot- 
hill ecotype, but they are survivors and pos- 
sibly even successful competitors in the alpine 
environment. 

This seems to indicate that there has been a 
recombination of genes determining morpho- 
logical and physiological characteristics, and 
that latent possibilities not yet expressed in 
the evolution of Potentilla glandulosa have 
been released. These findings may prove to 
be of general importance in plant breeding. 

Data from at least four years are needed 
from the three stations before the observed 
reactions can be interpreted with confidence. 
It should^ therefore, be possible to conclude 
the selection experiment after the season of 
1942. 

Status of Present Knowledge 

Experimentation continues to disclose the 
great variability in nature. Some variations 
appear to express only the richness of possi- 
bilities connected with the unfolding of life, 
whereas others serve the more utilitarian pur- 
pose of adapting plants to various kinds of 



environment. There is no basic difference 
between the two kinds of variation, but the 
latter has led to the development of regional 
ecologic races, the ecotypes. 

The separation of living things into species 
by development of genetic barriers is a second- 
ary phenomenon of great importance for 
evolution but of no immediate consequence 
for the adaptation of forms to their environ- 
ment, or for their survival. 

Furthermore, as indicated by the recom- 
binations in the selection experiment, genes 
evidently determine both morphologic and 
physiologic characteristics of the ecotypes. 
Also, certain plant groups have latent evolu- 
tionary resources to be released through the 
crossing of races from very different climates. 

How did these climatic races originate? 
We frankly admit that we do not know. A 
constantly increasing mass of evidence indi- 
cates that environment acts as a sieve that 
sorts out different hereditary forms into suit- 
able ecological niches by eliminating types 
not in harmony with it. Also it is observed 
that different recombinations of climatic races 
are produced through interbreeding; but how 
the governing genes originated is still a theo- 
retical problem. 

Much general observational evidence proves 
that climatic races differ markedly in their 
physiologic properties. Likewise, the recom- 
binations indicate that genes are at the base 
of the climatic reactions, but it is not known 
how genes govern the physiologic processes, 
nor how the latter are related to the striking 
reactions of plants to different environments. 

The data thus far obtained have been of a 
qualitative sort that outline facts of general 
biological importance. They should be sup- 
plemented, however, with quantitative data 
from which it would be possible to determine 
the fundamental physiological characteristics 
governing organisms in their respective en- 
vironments. Perhaps no questions in biology 
hold greater interest than how organisms 
meet the problems forced upon them by 
environment, how their reactions are related 
to their physiological capabilities, and how 
the latter are related to heredity. 



164 



CARNEGIE INSTITUTION OF WASHINGTON 



DESERT INVESTIGATIONS 

Forrest Shreve, T. D. Mallery, Edith B. Shreve, and W . V. Turnage 



Desert Vegetation and Flora 
Investigation of the botanical features of 
the North American Desert has been largely 
devoted to work in the northern states of 
Mexico. This has been necessary because both 
the floristic and the vegetational features are 
much less well known for Mexico than for 
the southwestern United States. With the 
exception of a few local studies, nothing has 
been done toward delimiting and describing 
the types of vegetation represented in northern 
Mexico. The desert flora of Mexico is incom- 
pletely known because it has not been rich 
enough to attract private or institutional 
collectors. 

The work now in progress embraces the 
study of both vegetation and flora. The 
former involves recognition of the various 
plant communities, the discovery of their ex- 
tent and boundaries, and the study of their 
relations to climatic and soil conditions. 
Thorough knowledge of the flora is an essen- 
tial basis for vegetational work, for investiga- 
tion of the floristic history of the desert, and 
for all work on the plant resources of the 
region. 

Preparation of manuscript embodying the 
results of work on the vegetation of the 
Sonoran Desert has been one of the principal 
activities of the year. Seven subdivisions of 
the area have been delimited and are given 
separate treatment. These range from the 
very arid region at the head of the Gulf of 
California and in the "rain shadow" of the 
San Jacinto, Cuyamaca, and San Pedro Martir 
Mountains, to the foothills of the Sierra 
Madre, in Sonora, where desert habitats are 
closely interlocked with open thorn forest or 
evergreen oak woodland. From the former 
area to the latter the rainfall increases from 
about 4 inches to about 14 inches. Also there 
is an increase in the percentage of the annual 
total which falls in the summer months. To 
the treatment of the natural vegetation will 
be added a section describing a number of 
the dominant plants. This section will include 
maps showing distribution, description of 



such characteristics of the plants as cannot be 
learned from herbarium specimens, and as 
much as it has been possible to find out about 
the habitat requirements and life histories of 
the plants. A large collection of living plants 
from the remoter parts of the Sonoran Desert 
is still contributing to this phase of the work. 

During the year Dr. I. L. Wiggins has 
made substantial progress in the preparation 
of the Flora of the Sonoran Desert, which 
will be published in conjunction with the 
volume on the vegetation. Manuscript has 
been completed for the Leguminosae, and 
the cooperation of Dr. J. R. Swallen, of the 
Smithsonian Institution, has been secured for 
the text on the Gramineae. These families, 
with the Compositae, will form nearly one- 
third of the entire flora. Manuscript has also 
been completed by Dr. Wiggins for a large 
number of the smaller plant families. 

Investigation of the Chihuahuan Desert 
was begun in 1938 as a five-year program 
organized after the plan of the Sonoran 
Desert, project and with similar aims. Two 
field seasons have now been given to the 
work, with fruitful results on both vegetation 
and flora. 

Dr. Shreve and Dr. Mallery spent two 
months in northern Mexico in the summer of 
1939, visiting areas not covered in the work 
of the previous year. The southwestern and 
southern edge of the Chihuahuan Desert was 
explored in the states of Durango, Zacatecas, 
and San Luis Potosi, making it possible to 
draw the boundaries of the desert in that 
region. Only in northern Coahuila are the 
limits of the desert yet to be determined. In 
setting the limits of the Chihuahuan Desert 
it has been found important to give some 
study to the areas which are adjacent to it 
but definitely not a part of the desert. The 
criteria employed are the physiognomy of the 
vegetation, the structure of the communities, 
and the floristic composition, and an effort is 
made to give equal weight to the three. 

On its western edge in Chihuahua the 
desert merges rapidly into grassland in a 



DIVISION OF PLANT BIOLOGY 



165 



transition similar to that which is spread over 
a broader area in western Texas and New 
Mexico. In southern Durango and northern 
Zacatecas there are extensive grasslands lying 
from 500 to 1000 feet higher than in Texas 
and northern Chihuahua. The transition 
from desert to the southern grasslands in- 
volves the occurrence of a broad belt of vege- 
tation which has been designated "cactus 
savanna." With a continuous or broken sod 
of grasses, this vegetation is dominated by an 
open stand of Acacia tortuosa and two erect 
platyopuntias, Opuntia streptacantha and O. 
durangensis, which reach a height of 15 to 
20 feet. The fact that the dominant plants 
of this vegetation occur neither in the desert 
nor in the grassland makes it necessary to 
regard the cactus savanna as a distinct type 
of vegetation rather than a transition. 

Grasses are somewhat more abundant in 
the Chihuahuan Desert than in the Sonoran, 
except on the extensive areas of limestone. 
On the sterile and poorly covered gypsum 
plains at 5000 to 5500 feet there is often a 
very open stand of Bouteloua Rothroc\ii. In 
northeastern and eastern Chihuahua there are 
numerous undrained basins, over the area 
commonly designated on maps as the "Bolson 
de Mapimi." Some of these receive the drain- 
age of large streams rising in the Sierra 
Madre Occidental, and consist of an alkaline 
plain with a central dry lake. The vegetation 
is low and open, with species of Atriplex 
dominating it. The undrained basins which 
receive only local drainage have a central floor 
covered with deep alluvial soil and dominated 
by nearly pure stands of Hilaria mutica. Al- 
though these llanos are often from 10 to 20 
miles in diameter, they are not to be regarded 
as part of the true grassland formation. The 
outwash slopes surrounding them are covered 
with characteristic desert vegetation. Such 
local grasslands, like the very local forests of 
larger trees, must be regarded as edaphic 
desert associations. Similar but smaller areas 
of Hilaria are found in the Sonoran Desert 
at elevations of 500 to 1000 feet. 

The eastern and southeastern boundary of 
the Chihuahuan Desert is sharply drawn in 
many localities by the Sierra Madre Oriental. 



In other places it merges rapidly into the arid 
bushland which covers the plains of Nuevo 
Leon or into a less arid and heavier bushland 
characteristic of elevations above 5500 feet in 
Zacatecas and San Luis Potosi. The occur- 
rence of heavy bushland, and the conditions 
which favor it, is found to set the southern 
limit of many of the characteristic plants of 
the Chihuahuan Desert. For example, Larrea 
and Flourensia are very uncommon in the 
heavy stands of shrubs, and in spite of their 
ability to take advantage of increased supplies 
of water they are doubtless here limited by 
unfavorable conditions for germination and 
early growth. 

On the isolated mountains of the Chihua- 
huan Desert, with basal elevations of 4000 to 
5000 feet, there is a very gradual change in 
vegetation with increasing altitude. Oaks and 
pinyons occur in favorable locations about 
2000 feet above the floor of the desert, but 
characteristic desert plants range much higher 
than the lowest occurrences of trees. In 
northern Zacatecas Larrea, Ephedra, Yucca, 
Dyssodia, and other desert species were found 
at an elevation of 8600 feet, associated with 
Pinus pinceana, P. cembroides, Lindleyella 
mespiloides, and juniperus mexicana. 

The preparation of a Flora of the Chihua- 
huan Desert has been undertaken by Dr. I. M. 
Johnston, of the Arnold Arboretum of Har- 
vard University. Organization of this work 
has been begun, and Dr. Johnston has found 
himself favorably located for consultation of 
nearly all the early collections of plants made 
in northern Mexico. The principal needs in 
the floristic work are collections from the 
poorly explored central part of the area, and 
adequate material to give a better knowledge 
of the geographic ranges of both common 
and infrequent plants. In the summer of 
1938 Dr. Johnston made a collection of 1000 
numbers, which proved to be particularly rich 
in novelties from the arid central basins and 
the gypsum soils. In the summer of 1939 Dr. 
Shreve and Dr. Mallery secured about 500 
plants, which were placed in Dr. Johnston's 
hands for study. Through the cooperation of 
Dr. H. H. Bartlett, of the University of 
Michigan, Dr. Johnston also received a set of 



i66 



CARNEGIE INSTITUTION OF WASHINGTON 



1600 plants collected in 1939 by Mr. Stephen 
S. White and Mr. LeRoy H. Harvey in the 
Chihuahuan Desert and adjacent regions. 

Rainfall 

Mr. Turnage and Dr. Mallery have pre- 
pared for publication a paper entitled "An 
Analysis of Rainfall in the Sonoran Desert 
and Adjacent Territory." This contribution 
is based on all the general and special rainfall 
observations made at the Desert Laboratory 
over a period of more than 20 years, on the 
U. S. Weather Bureau records for the terri- 
tory involved, and on the records of the 
Mexican Meteorological Service for stations 
in Sonora. The amounts and seasonal distri- 
bution of rainfall have been determined, and 
the dynamics of the summer and winter rain- 
storms has been analyzed. The larger geo- 
graphic influences and the local topographic 
ones have been discussed. Stations on the 
slopes of low mountains or on abrupt peaks 
have a rainfall below the normal for the 
region, while those on the slopes of high 
mountains, in deep canyons, or to the leeward 
of higher land have a rainfall above the 
normal. These influences are more potent in 
the winter period than in the summer. In 
the northwestern half of the Sonoran Desert 
the winter rain exceeds the summer rain, but 
in the southeastern half the reverse is true. 
A relatively high percentage of winter rain 
is found in the parts of Arizona which are 
dominated by a type of chaparral closely re- 
sembling that found in the winter rain belt 
of the Pacific Coast. In the southeastern part 
of the Sonoran Desert the most favorable 
habitats are occupied by thorn forest, a forma- 
tion which dominates the region immediately 
south of the desert, in which from 70 to 80 
per cent of the rain falls in the summer. In 
the central part of the Sonoran Desert indi- 
vidual showers are more erratic from place 
to place in summer than in winter. For the 
winter season as a whole, however, the rain 
is more erratic from spot to spot in a small 
area than is the rain of the entire summer 
season. Concomitant rainfall variations in 
space and time show the winter season to 
have more marked extremes than the sum- 



mer. When rainfall is plotted against eleva- 
tion, the area investigated can be divided into 
three geographical regions in winter and four 
in summer, the stations grouping themselves 
around a curve calculated by the method of 
least squares. The scatter of the stations away 
from the several curves can be interpreted as 
due to the nearness of the station to another 
region or to the relief of the land in the 
vicinity. The normal rainfall is greater in 
relation to altitude in the southern part of the 
Sonoran Desert than in the northern. The 
opinion is expressed that little more can be 
learned from continued observations of rain- 
fall at the present sporadically located series 
of stations. A new approach to the study of 
rainfall is now desirable, from the meteor- 
ological rather than the climatological stand- 
point. Important needs are the study of topo- 
graphic influences, the investigation of rain- 
fall patterns in small areas, and supple- 
mentary studies of rainfall intensity, runoff, 
and soil moisture. 

Evaporation 

Mrs. Edith B. Shreve has continued her 
investigation of evaporation with a view to 
securing a reliable norm which can be used 
in evaluating the rates of transpiration from 
plants. The work has been directed toward 
testing the Livingston atmometer, which has 
been criticized as not giving readings which 
are proportional to a wide range of the condi- 
tions which determine evaporation and 
greatly influence the water loss of plants. 
Porous plates 2 mm. thick, of various sizes 
and shapes, were connected to a source of 
water and exposed to the air in positions 
simulating those of plant leaves. Evaporation 
rates per unit area were measured under 
many kinds of natural conditions and under 
various controlled conditions of temperature, 
humidity, and wind velocity. The shape and 
angle of exposure of the plates were found 
to be of relatively small importance as com- 
pared with the area. The evaporation per 
unit area was found to vary inversely with 
the 0.3 power of the area under all conditions. 
These conditions included wind velocities 
from to 20 miles per hour, temperatures 



DIVISION OF PLANT BIOLOGY 



167 



from 108 to 45 ° F., and wet-bulb depres- 
sions from 30 ° to io°. The role of the area 
of the porous plates in their evaporation per 
unit area indicates that comparison of the 
rates of transpiration from plants of different 
leaf size may lead to erroneous conclusions. 
Water losses from the same plates were meas- 
ured simultaneously with those from the 
atmometer. The relation was linear for any 
one size for all conditions and can be ex- 
pressed as a simple ratio E/E', in which E 
is the evaporation from the plates and E' that 
from the atmometer. However, the ratios 
change with area according to the equation 



E/E' = 2.5/ A- 3 . If transpiration per unit area 
from a plant is substituted for evaporation 
from the plates, and the size of an average 
leaf is used for the area, an expression is 
obtained which can be used to evaluate trans- 
piration in terms of the evaporative condi- 
tions of the environment. If the expression 
T /Ex 2.5/ 'A- 3 is used, where T is the transpi- 
ration per unit area, E the evaporation per 
unit area from the atmometer, and A the area 
of a leaf of average size from the plant used, 
then the Livingston atmometer may be used 
as a norm in the investigation of the water 
relations of plants. 



ECOLOGY 



Adaptation and Origin 



F. E. Clements, F. L. Long, and E. V. Martin 

Evaporation and transpiration under con- 
trolled conditions. In the attempt to evaluate 
the functional responses of adapted plants, 
experiments have been carried on in a dark- 
room as completely sealed as possible by 
means of a metal lining. These have dealt 
with evaporation from wet blotting paper and 
transpiration from Helianthus annuus and 
Ambrosia trifida, with the atmospheric fac- 
tors under control. The latter ranged from 
15 to 85 per cent relative humidity and 80 ° 
to 120 F., with wind velocities around 500 
ft./min. Evaporation from wet blotting paper 
(essentially a free-water surface) follows the 
known laws, being proportional to the dif- 
ference between the saturation vapor pressure 
at the temperature of the evaporating surface 
and the vapor pressure in the surrounding 
atmosphere. Wind increases the rate of evapo- 
ration, with a consequent increase in the fac- 
tor of proportionality between evaporation 
rate and vapor-pressure difference. 

The transpiration of Helianthus annuus 
(both Russian Mammoth and selfed Canadian 
strains) and Ambrosia trifida seems to be 
practically identical under given conditions 
of air temperature and relative humidity, in 
the absence of wind and radiation. The rela- 
tion between transpiration rate and relative 
humidity at a given temperature appears to 



be linear throughout the humidity range. At 
a given relative humidity the transpiration 
rate at 120 F. was four times that at 8o° F. 
These ratios are quite different from those 
obtained for evaporation from wet blotting 
paper; the evaporation rate at 120 was about 
1.35 times that at ioo° and 1.90 times that 
at 80 °. An interesting point was the discovery 
that at 120 F. transpiration and evaporation 
were very nearly equal; in other words, at 
this temperature leaves behaved almost like 
free-water surfaces. However, at 80 ° F. the 
rate of transpiration was only about half that 
of evaporation. The explanation may lie in 
an increase of the permeability of the cuticle 
with the higher temperatures, or in a change 
of protoplasmic properties. 

Evidence in support of this hypothesis was 
obtained from experiments dealing with the 
effect of wind on the transpiration rate. A 
velocity of 500 ft./min. increased the transpi- 
ration rate 15 to 25 per cent at a temperature 
of 8o° F., about 50 per cent at ioo°, and 
between 200 and 300 per cent at 120 . These 
values are in contrast with an increase of 
500 per cent in rate of evaporation from the 
blotting paper at this velocity. The calcula- 
tions of Brown and Escombe show that wind 
should increase the stomatal component of 
transpiration in Helianthus annuus only 
about 25 per cent, which appears to be nearly 
the value obtained in these experiments at 
an air temperature of 80 ° F. As the temper- 



CARNEGIE INSTITUTION OF WASHINGTON 



ature increases, however, the leaves more 
nearly approach the blotting paper in be- 
havior, indicating an increase in the cuticular 
component of transpiration. 

Transpiration at all three temperatures em- 
ployed exhibited a very close correlation with 
the vapor-pressure deficit of the atmosphere, 
and did not follow the laws controlling 
evaporation from a free-water surface as 
represented by the wet blotting paper. 

The temperatures of blotting paper and 
leaves were measured by means of thermo- 
couples. It was found that Newton's law of 
cooling held over a range of about 20 ° C; 
beyond this limit the relation departed slightly 
from linearity. The maximum cooling of 
leaves at an air temperature of 120 F. was 
13 ° C, although at an air temperature of 
about 140 F. a drop of 20 ° C. below the air 
temperature was observed. The rates of tran- 
spiration ordinarily found in nature will sel- 
dom produce depressions in leaf temperature 
of more than io° C. below air temperature. 

Transpiration rates of native transplants. 
The following comparisons are drawn from 
native transplants grown in phytometer con- 
tainers at the Alpine Laboratory. In 32 inde- 
pendent comparisons of the rate of transpira- 
tion in sun and shade forms of a given species 
(21 species being tested), it was found that 
when both forms were in the shade, in 25 
cases the difference between them was not 
statistically significant. However, with both 
forms in sunlight this was true of but 17 
cases. In 14 instances, the sun form main- 
tained a higher rate of loss than the shade 
plant, and in 1, the reverse was true. 

In testing the response of climatic forms, 
it was found that for 6 species, the plants at 
the plains and montane gardens had the same 
rates in a given environment, while for Heli- 
anthus annuus the plains form gave a slightly 
lower rate than the montane. Nine compari- 
sons were made between montane and alpine 
forms; in 2 the forms were equivalent, in 
3 the montane plants yielded the higher rates, 
and in 4 the alpine forms were higher. Plants 
grown in lath-houses at the three climatic 
stations indicate that the plains and montane 
shade plants have about the same transpira- 



tion rate in the same conditions, while the 
alpine shade plants have a somewhat higher 
rate of loss. 

When the various forms are tested in the 
habitats in which they are grown, the usual 
order in terms of transpiration rate is the 
following: plains highest, montane next, and 
alpine lowest, with the lath-houses at each 
station giving rates about half those in the 
sun at the same station. 

Transpiration of cut shoots from adapted 
forms. The water loss of cut shoots for 
3-minute intervals was determined by weigh- 
ing them on an analytical balance, using a 
number of species for each adaptation series 
at Santa Barbara. The data were restricted to 
a comparison of the rates per unit of leaf 
area of plants of a given species growing in 
the various habitats. Six species were utilized 
from the ridge and shelter gardens of the 
coastal sand dunes, both forms being tested 
side by side in the shelter habitat. No dif- 
ference could be detected in the response of 
Oenothera trichocalyx and Rudbecfya bicolor, 
but in the other 4, Antirrhinum hispanicum, 
Chrysanthemum coronarium, Agrostemma 
githago, and Gaillardia hybrida, the rates for 
the ridge forms were but 65 to 85 per cent 
as high as for the shelter-garden plants. In 
all species, the ridge plants are so much 
smaller than the latter that the total transpi- 
ration per plant would be several times as 
great in the shelter garden. 

For comparing the rate of transpiration in 
sun and shade shoots, 7 species were employed 
from this series (approximately 100, 50, and 
12 per cent light intensity), and 6 from the 
in-and-out huts with branches of the same 
plant in sun and in shade. Of 18 sets, each 
with an average of four trials, 2 gave a lower 
rate for the shade than for the sun, 3 gave 
equal rates, and in 13 the rate for the shade 
form was from 20 to 400 per cent greater. 
For the in-and-out species, the rates for the 
"in" shoots were in all instances lower than 
for the "out" ones, the ratios being from 
37 to 79 per cent. 

In the fertilizer-water series, namely, 
NW-o, NW-i, and NW-2, five species exhib- 
ited decreasing transpiration rates in this 



DIVISION OF PLANT BIOLOGY 



169 



order. The plants in NW-o gave an average 
rate about twice that in NW-2, while those 
in NW-i were fairly intermediate. In the soil 
pits, the plants grown in sand and clay 
yielded higher rates for three species than 
those in garden loam. Comparable results 
were obtained for the length-of-day series, as 
well as for Mimulus cardinalis in four 
adapted sets, viz., nutrient-water, soil pit, sun 
and shade, and length of day. 

Phytometcr measurements in factor series. 
A phytometer battery of 10 plants of Heli- 
anthus annuus was installed in each of the 
following habitats: dune ridge, shelter gar- 
den, sun main garden, 9- and 5-hour length- 
of-day sheds, and lath-houses with 75, 50, 25, 
and 12 per cent light intensity. The results 
were as shown in the accompanying table. 



pressed in units of grams per square decimeter 
per week over a 9-week period. 



Habitat 


Total 

dry wt. 

(g.) 


Total 

transpira- 
tion 
(g.) 


Water 
require- 
ment 
(g./g.) 


Ridge garden .... 
Shelter garden . . . 

Main garden 

Lath-house 75 %. 
Lath-house 50 %. 
Lath-house 25 %. 
Lath-house 12 %• 

9-hour shed 

5-hour shed 


1.05 

5.93 

49.10 

34.60 

17.70 

9.20 

3.10 

21.71 

9.20 


394 
1490 
7241 
5614 
3254 
1781 

800 
3981 
2382 


385 
254 
147 
162 
184 
194 
258 
183 
259 



Transpiration rates in g./dm. 2 /day were cal- 
culated for weekly intervals during a period 
of 7 weeks. The average rate was 13.6 for 
the ridge and 13.7 for the shelter garden. 

Dry-weight increment of four series. Bat- 
teries of 64 free phytometers (Helianthus 
annuus)" were transplanted to each of twelve 
different habitats in the adaptation gardens 
for measuring the rate of growth as recorded 
by dry weight. Eight plants of these were 
harvested each week for a period of 8 weeks. 
With few exceptions, the weekly increments 
in the various habitats bear a relation to each 
other corresponding to the final dry weights 
shown in the accompanying table. The rela- 
tive increment ("net assimilation rate" of 
Gregory) was derived by dividing the dry 
weight by the average leaf area, and is ex- 



Habitat 


Final 
dry wt. (g.) 


Relative 
increment 


Ridge garden 

Shelter garden 

NW-0 (main garden).. . 

NVV-1 

NW-2 


0.35 

1.48 

31.90 

56.20 

72.40 

50.60 

12.70 

0.81 

25.90 

15.85 

4.12 

0.82 


0.158 
0.292 
0.539 
0.631 
0.706 


Loam 

Adobe 

Sand 

Lath-house 75 % 

Lath-house 50 % 

Lath-house 25 % 

Lath-house 12 % 


0.556 
0.356 
0.156 
0.362 
0.267 
0.173 
0.070 



This experiment was duplicated for five 
habitats, employing batteries of 150 plants 
and determining the leaf area and dry weight 
of 25 each week for 6 weeks, the resulting 
values being comparable with those above. 
Similar determinations were made for the 
three climatic and ten edaphic stations at the 
Alpine Laboratory in 1939, and the results are 
undergoing further check during the current 
season. 

In the continued endeavor to develop a 
short, compact form of sunflower, especially 
adapted to the requirements for phytometers, 
a new strain, PU, has been obtained from 
Canadian S-490, supplied by the Department 
of Agronomy of the University of Saskatche- 
wan. The individuals were far more uniform 
than in the other strains grown, the coefficient 
of variability for stem height being 1.55 per 
cent, as compared with 20.51 per cent for the 
red sunflower. For leaf area the coefficient 
was 4.59 per cent, the next lowest, 7.75 per 
cent, being found in the Russian Mammoth. 

Climate, Climax, and Conservation 

F. E. Clements and E. S. Clements 

The drought decade and sunspot numbers. 
The prediction that the recent sunspot maxi- 
mum would reflect the double cycle and reach 
a yearly mean of more than 100 has been 
verified by a plateau of three years with an 
average of 104 spots. This followed the work- 



170 



CARNEGIE INSTITUTION OF WASHINGTON 



ing rule in being accompanied by a period 
of generally intense drought. It was further 
assumed that the number would drop rapidly 
in the fall of 1939, the drop to mark the 
beginning of good rains in California and a 
precipitation above normal for the West as 
a whole. This assumption proved correct for 
southern California and is in process of being 
justified elsewhere. 

The seasonal distribution of rainfall during 
the three years of the plateau appears also to 
bear a close relation to the monthly sunspot 
means. For the most part, late spring and 
summer were very dry, coinciding with a 
5-month average of 128 spots in 1937, 122 
in 1938, and 108 in 1939. Months with low 
spottedness in the early spring were generally 
about normal, and similar months in autumn 
were likewise more or less rainy. Such a 
correspondence has been noted a number of 
times in previous years, but the existence of 
a rule is still to be determined. Theoretically, 
it is logical to expect that abrupt changes in 
number during the year will produce effects 
resembling those of like changes from year 
to year. 

It is well understood that a major difficulty 
in verifying forecasts arises from the seem- 
ingly fortuitous variations in rainfall from 
region to region, a situation complicated by 
the present necessity of keeping records by 
states and sections. In order to evaluate this 
factor more closely, an analysis has been made 
for the critical tier of prairie states, viz., 
North Dakota to Texas, for the past decade. 
In the five years of serious drought, 1931, 
1933, 1934, 1937, and 1939, all the states 
agreed in exhibiting a minus departure, and 
the accord for 1930 was nearly complete. For 
the one good year, 1935, South Dakota alone 
gave a minus departure, while for the rela- 
tively good year 1938, South Dakota and 
Texas recorded 88 per cent of the normal at 
one extreme and Kansas 102 at the other. 
For 1932, there were four plus and two minus 
values, but none of these was excessive in 
amount. Nebraska and Kansas gave the same 
sign for every year of the decade; North and 
South Dakota were in harmony each year but 



one, and Oklahoma and Texas were in 
moderate disagreement for two years. 

The variation to be reckoned with in fore- 
casting the rainfall of a particular state may 
be illustrated by the case of Nebraska. Since 
1 87 1 there have been but 4 years in which 
all stations showed minus signs and but 2 in 
which all departures were plus. On the other 
hand, the departures for 28 of the past 46 
years, in which the number of stations ex- 
ceeded 50, have amounted to 2 inches or more 
and have concerned three-fourths of all sta- 
tions. In 9 other cases, the difference has been 
less than 1 inch and hence of little signifi- 
cance, while for the remaining 9 years the 
average departure has been between 1 and 
2 inches and not critical. 

A method of compensation for drought. 
Though drought periods are now known to 
be recurrent and inevitable, it is not yet 
realized that the methods of compensation 
and conservation available are adequate to 
eliminate their major effects. The various 
processes concerned have been developed inde- 
pendently, and the present need is to organize 
them into a complete system for evading 
drought. The first task is to bring about their 
proper coordination, and this can be done 
only by practical tests, such as have been 
proposed. 

An adequate system of compensation must 
take into consideration the advance made in 
long-range forecasting during the past decade. 
In this period the predictions of monsoon 
rains in India have achieved a rating of 82 
per cent, and this record has been approached 
by several investigators in the United States. 
The present need is to test the various indices 
in a much larger number of areas and regions 
and to determine their value for anticipating 
seasonal distribution as well as the annual 
departure. In addition to rainfall, it is pos- 
sible to forecast temperatures and consequent 
evaporation, both of which are concerned in 
the fate of the water that enters the soil. The 
amount of moisture in the soil at any time 
is easily determined and, with the record of 
its changes from time to time, affords an 
invaluable prediction of probable crop yields. 
The most striking application of this method 



DIVISION OF PLANT BIOLOGY 



I 7 I 



has been to fields of winter wheat with sum- 
mer fallow, where it all but insures the 
equivalent of an average annual crop, but it 
can be applied with similar success to other 
cultivated and native crops. 

In dry years or arid regions, only about a 
third of the rain that falls becomes available 
to plant roots. The major portion is lost 
through interception, runoff, and evaporation 
from the soil surface. Loss by interception is 
governed by the type of rain and the kind of 
cover, and is practically unavoidable. On the 
other hand, runoff may be reduced to the 
vanishing point, and evaporation may be cut 
down to a fourth or less of the normal. Such 
savings constitute the direct compensation for 
drought and aridity; appropriate measures 
have been extensively developed and only 
await decisive test through incorporation in 
the compensating system. The problem of 
filtering water into the soil, with correspond- 
ing control of runoff, erosion, and flooding, 
has been largely solved and the process re- 
quires only certain refinements. At present 
these involve chiefly the interaction of cover 
and intimate structures, such as small furrows 
or trenches, though ultimately the major 
reliance will be placed upon plant life. In the 
steps to be taken for reducing evaporation 
losses from the soil, stubble, straw, hay, and 
dry weeds constitute the outstanding ma- 
terials. Dead rooted cover surpasses all other 
types of mulch in total effectiveness when 
penetration, control of wind and water, 
evaporation, and transpiration losses are taken 
into account. 

In the study of succession in abandoned 
fields, recovery was found to be far more 
rapid after the sketchy tillage of the "suitcase 
farmer" than elsewhere. Shallow plowing at 
the outset and the practice of drilling seed 
for the next wheat crop into the headed stub- 
ble without further cultivation explained the 
good tilth and the persistence of grass crowns 
and rhizomes. What was generally regarded 
as a shiftless practice was actually a new way 
of securing the values just mentioned, and in 
addition a fair control of weeds with their 
high transpiration waste. It was further as- 
sumed that this control could be rendered 



nearly as complete as that with bare summer 
fallow by using a subtiller blade to sever the 
roots and at the same time loosen the soil 
without turning it up. An additional ad- 
vantage is that of maintaining the soil profile 
in its optimum nutrient relations, a factor too 
often overlooked in the traditional "good" 
tillage. For this purpose several implements 
are now available, but the most satisfactory 
are those that leave the headed stubble up- 
right. With sufficient draft, it will become 
feasible to carry out harvesting and subtilling 
in one operation. 

Two other features of critical import are, 
first, a prompt and accurate land-use survey, 
by which crop lands may be set aside from 
range or fields to be regrassed, on the basis 
of the methods outlined above; second, crop 
adjustment to the soil-water capital and the 
probable rainfall, together with crop special- 
ization, which is already well advanced 
through the efforts of the various experiment 
stations. Finally, application of the principles 
and methods of bio-ecology is essential to the 
treatment of each farm as an organized unit, 
and has definite though indirect effect in 
minimizing the impact of drought, both eco- 
nomically and socially. Control of rodents 
and predators of all kinds, game management 
for waterfowl, quail, grouse, and pheasants, 
ponds for fish, muskrats, and beaver, and 
proper stocking with the various domestic 
animals will afford full scope for establish- 
ing a working balance between plants and 
animals on the farmstead. 

Installation of experimental grids. Public 
discussion of the necessity of purchasing 
marginal farms and returning them to grass- 
land has led to the general assumption that 
this is a simple matter and one easy of ac- 
complishment. The facts, however, are quite 
otherwise, for the desultory attempts to reseed 
depleted areas of climax grassland during the 
past thirty years have regularly eventuated in 
failure. Success has been more frequent in 
the recent projects of the Soil Conservation 
Service, but it is still the exception rather than 
the rule. When proper account is taken of 
the vast extent of original climax prairie, its 
wide range of climate, and the large number 



172 



CARNEGIE INSTITUTION OF WASHINGTON 



of associations and faciations and the many 
types of disturbance and stages of succession 
in it, it is evident that no simple set of proc- 
esses and groups of materials will prove ade- 
quate to the task. To blaze trails through 
such a maze of conditions and species is a 
formidable undertaking, and one which will 
be ?s continuous as progress in all other agri- 
cultural fields. But it is different in having 
almost no background of experience or knowl- 
edge, and the pressure of events is such that 
it cannot await the slow piecemeal acquisition 
of the necessary facts. To meet this need 
promptly and adequately, the method of 
experimental grids has been developed to 
organize large numbers of field and evalua- 
tion plots into a comprehensive system, with 
checks and comparisons as major tools. 

As a quantitative method of studying fac- 
tors, processes, and living materials in the 
field, the grid ranks with the quadrat and has 
an equally wide range of uses. Perhaps its 
greatest value lies in closing the gap between 
nursery beds or test plots and large-scale 
operations on projects, and in providing 
answers much more rapidly, cheaply, and 
certainly than these can. Its chief purpose at 
present is to solve quickly the many detailed 
questions that have arisen in connection with 
regrassing, especially by seeding, but it has a 
place wherever experimental results are 
needed to guide field operations. It may be 
applied to cultivated fields, highway land- 
scaping, wood lots, windbreaks, forest plant- 
ing, game refuges, etc., whenever it is desir- 
able to replace personal observations and 
judgments with quantitative results and 
standards. 

The standard type of grid is designed to 
compare the performance of as many species, 
methods, and processes as a project may de- 
mand. By contrast, a special grid may con- 
fine itself to one factor or process, such as 
adaptation, acclimatization, competition, rate 
and date of seeding, mulches, structures, etc. 
The two types may be combined to form a 
master grid, in which the standard form is 
supplemented by one or two special grids 
near at hand or in the same general locality. 
A typical grid drawn up for the mixed prairie 



of the Great Plains comprises ten of the most 
important grass dominants, two introduced 
grasses, and a mixture of mid-grasses, of 
short-grasses, and of mid- and short-grasses. 
These are crossed by untilled and subtilled 
nurse plots, similar mulch plots, a pair with 
small trenches 1 1 / 2 and 3 feet apart, and still 
others with fertilizer and with native and 
cultivated legumes. A competition grid con- 
sists of a number of selected species of grasses, 
with or without forbs or shrubs, crisscrossed 
to match each species with all the others. The 
adaptation grid is devised to reveal the quali- 
ties of climatic and edaphic strains of grasses 
especially, and to show the rate and degree 
to which these may be modified in a series 
of regions. 

Though the immediate objective of grid 
installations is to meet the practical needs of 
conservation projects, it is evident that they 
will make an increasingly important contri- 
bution to the experimental and quantitative 
foundation of dynamic ecology. It is fortu- 
nate that the principles and methods of the 
latter are undergoing test on such an exten- 
sive scale. This novel cooperation will be to 
the great advantage of both ecological re- 
search and practice. 

The ecological basis for regrassing. 
Throughout the grassland climate and cli- 
max, the grass cover will be restored by the 
natural process of succession when the dis- 
turbance ceases wholly or in large part. The 
rate at which this restoration takes place 
depends primarily upon the supply of seeds 
or other parts; it is rapid wherever rootstocks 
have persisted in the soil, and exceedingly 
slow when seeds must come in from neigh- 
boring pastures and roadsides, as is the usual 
case. The rigor of conditions as to germina- 
tion and seedling establishment often plays a 
decisive part likewise, notably in the hot, dry 
desert plains of the Southwest. On the lower 
levels of this association, the grass relicts are 
so small and few, the soil is so depleted by 
erosion, and temperature and evaporation 
are so excessive that succession is all but im- 
possible, and the disclimax desert scrub will 
remain in possession for a long time to come. 
In consequence, natural succession can be 



DIVISION OF PLANT BIOLOGY 



173 



depended upon for recovery only under excep- 
tional circumstances, and for rapid restoration 
must be supplanted by artificial methods that 
speed it up greatly. 

However, the requirements for success with 
artificial succession are essentially identical 
with those for the natural process. The ruling 
disturbance must be stopped, as well as such 
accessory ones as grazing and rodent action; 
seed must be supplied in large amount and 
properly planted, infiltration increased, ero- 
sion and evaporation diminished, and compe- 
tition reduced to a minimum. The proba- 
bility of securing an adequate stand will be 
enhanced if seeding is done in the light of 
the record of soil moisture and with some 
consideration of the rainfall cycle in general 
and the special pattern of the region con- 
cerned. The ecological rule is to reproduce 
the natural process in essentials but to tele- 
scope the stages into two or three at the most 
by controlling conditions and greatly increas- 
ing the seed supply. In the case of such 
vigorous colonizers as sand dropseed or 
crested wheat grass, a dense, pure stand may 
be obtained the first year in the proper climate 
for each, but this will probably not be the 
final stage, as indicated later. 

A significant corollary to the principle of 
adaptation is to the effect that native species, 
particularly climax grasses, are better suited 
to their particular subclimate than are alien 
ones. This not only is logical from the theo- 
retical standpoint, but also derives strong sup- 
port from the results of a quarter-century in 
transplant gardens. It is also confirmed by 
the behavior of grass populations of one 
species drawn from different portions of its 
range." Thus, seeds of blue grama from the 
northern Great Plains have been found to 
germinate and to bloom and set seed earlier 
than those from the southern, and the plants 
are but a third or a fourth the size. Plants 
from intermediate stations only a few hun- 
dred miles apart form distinct intergrades in 
all these respects. These constitute new ac- 
quired characteristics of less fixity within the 
more permanent climatic pattern fixed much 
earlier in terms of boreal or northern ("win- 
ter") grasses and subtropical or southern 



("summer") ones. The extent to which such 
climatic and edaphic strains can be modified 
by different environments is now being in- 
vestigated on a much larger scale by means 
of regional grids. 

Crested wheat grass, a native of Eurasia, 
has made such a remarkable record in Canada 
and the northern prairie states as to appear 
exempt from the rule mentioned above. With 
wider tests and more detailed records, how- 
ever, it is becoming evident that the exception 
is more apparent than real. Not only do 
some of the best natives give promise of ex- 
celling it in establishment and yield, but 
definite proof is being obtained to show that 
they exceed it in competitive equipment, and 
a number of installations are now being 
studied to test this point. However, although 
it is important to know the precise role of 
crested wheat grass in regrassing, it is less 
necessary as a practical matter. If this species 
maintains itself permanently on the range 
without some form of semicultivation, it will 
have justified its use, and if it gives way 
before the competition of the natives, a better- 
adapted cover will be in possession. From 
the preliminary evidence, crested wheat grass 
should turn out to be a "subclimax" grass in 
the artificial succession for regrassing. 

A different type of restoration, but one 
equally entitled to the term regrassing, has 
been well justified by the initial experiments 
and is now on the eve of being widely ex- 
tended by means of the grid method. This 
is the re-establishment of climax grassland by 
burning off the sagebrush, which today forms 
the characteristic disclimax of the Great Basin 
and extends well beyond its borders. No 
other method can compare with this in the 
quickness and cheapness with which a vast 
acreage can be returned to productive grass- 
land. This is said with full realization that 
fire is a dangerous tool and should never be 
employed except under competent and experi- 
enced direction. Regions differ much, how- 
ever, in physical conditions, in the age and 
stand of sagebrush, in the quantity and 
species of the grass relicts, and in the grazing 
system. Most critical of all perhaps is the time 
of burning, with respect to the rate at which 



174 



CARNEGIE INSTITUTION OF WASHINGTON 



the fire runs and the risk of injury to the 
grass. The immediate task is to perfect the 
method of burning for each distinct area by 
means of adequate grid installations and then 
to proceed with the practical program as 
rapidly as grazing demands warrant. 

The origin and nature of oa\ barrens and 
openings. From time to time these peculiar 
communities of the oak-hickory association 
of the deciduous climax have been studied in 
the course of field trips through the East, and 
an opportunity was found to compare them 
more in detail in the autumn of 1939. The 
floristics of the oak openings in Ohio have 
been extensively treated by Moseley, and the 
Kentucky barrens have been comprehensively 
discussed by Dicken. In spite of the differ- 
ence in name and the marked divergence of 
the soils, these are much alike in origin, in 
climatic and serai relations, in composition, 
and in problems of utilization. In essence, 
they are inclusions of the tall-grass post- 
climax swept into the deciduous forest from 
the southwest during the major warm-dry 
phase of the post-Pleistocene. With the return 
of the cool-moist forest climate, the grasses 
found refuge in the shallow limestone soils 
of the barrens or the sands of the openings, 
where conditions favored them in competition 
with trees. How narrow this advantage is 
may be readily seen from the invasion of 
small trees and shrubs in both communities, 
and there must always have been a succes- 
sional trend toward the climax, fluctuating 
with the climatic cycle and often upset or 
much modified by man. A similar phe- 
nomenon is to be observed in the Indiana 
dunes about Lake Michigan today, but the 
succession is still active and hence the stages 
are much more distinct. The same general 
relation of forest to prairie now prevails 
throughout the ecotone between them. What 
seems to be the same but is actually a reversed 
relation characterizes the Cross Timbers of 
Texas and the similar woodlands of Okla- 
homa, in which sand has provided trees with 
the needed compensation against a prairie 
climate. 

The origin of the prairie was a topic much 
debated before the rise of dynamic ecology, 



and various explanations continue to be 
offered by those little or not at all versed in 
vegetation. The evidence from paleo-ecology, 
however, permits no doubt that the prairie, 
like other great climaxes, is a product of 
climate and as such has been in existence for 
some millions of years. Throughout this time, 
it has been subject to climatic shifts and has 
moved forward or backward under the com- 
pulsion of warm-dry or cool-moist phases of 
major climatic cycles. Chief among these 
have been glacial-interglacial cycles, and the 
present distribution of the prairie bears the 
impress of the latest of these. As a conse- 
quence, prairie inclusions are still to be found 
far beyond their proper climate and have 
been a perennial puzzle to those unfamiliar 
with the history of vegetation. 

As such a great relict area, the barrens of 
Kentucky and neighboring states have been 
the object of all possible interpretations, 
among which fire has easily ranked first. 
Fire, however, could not have originated the 
grassy tracts, nor could it have extended them, 
since years of annual fires can do no more 
than reduce hardwoods to the condition of 
scrub. Clearing could have had only a second- 
ary minor effect, and the herds of buffalo 
practically none at all. By far the most proba- 
ble course of events was a climatic change 
toward dryness, marked by the forward 
movement of prairie, followed by a return of 
the moist forest climate (a rainfall of 45 to 
50 inches), the persistence of grassland areas 
on shallow limestone soil, readily dried by 
widespread underdrainage, the formation of 
swamps, especially canebrakes, followed by 
succession to savanna, and finally a wide 
range of disturbance effects, of which cultiva- 
tion and fire were the chief. 

The biotic significance of disturbance. 
Field observations to the effect that rodents 
in general prefer disturbed areas in grassland 
have been confirmed by the results from 
rodent-proof exclosures, in northern Arizona 
especially. These regularly contain a larger 
percentage of forbs than does the range out- 
side or the cattle-proof unit which is open to 
rodents. After the forbs had disappeared 



DIVISION OF PLANT BIOLOGY 



175 



from the latter, a small plot was fenced with 
hardware cloth, and the forbs reappeared in 
a few years, only to vanish again when the 
fence was removed. The preferences of 
prairie dogs have also been determined by 
noting the various species utilized for food. 
In one large town in the mixed prairie, 15 
species had been eaten to some degree, 
whereas none of the grasses had so far been 
touched. This by no means signifies that 
rodents do not consume grass, but the latter 
seems to be a second choice, except when forbs 
are few or hard, or a protected range adjoins 
a depleted area. A novel instance of this fact 
has occurred in recent years of drought, dur- 
ing which pocket gophers have moved out of 
pastures and meadows in large numbers, to 
occupy the better-watered, greener shoulders 
and shallow ditches of roadsides. In some 
cases the mounds are almost continuous, with 
a high density for a score or more of miles, 



constituting an infestation such as has never 
been observed in natural cover. 

The initial disturbance that leads to the 
invasion or increase of rodents usually results 
in renewed disturbance on a larger scale, 
which brings about a disclimax more or less 
typical of the species concerned. Though the 
change in composition may be pronounced, 
such areas are relatively quite insignificant 
and temporary, and commonly return to the 
climax condition within a few years after 
abandonment. No matter how great the 
control may seem at the maximum, all the 
grazing animals, from prairie dog and jack- 
rabbit to antelope and bison, wild horses and 
cattle, exert only a transient effect upon the 
climax. Their major influence is due to coac- 
tion and hence they are known as influents, 
by contrast with the plant dominants, which 
owe their mastery of the climax to reaction 
upon the habitat. 



PALEOBOTANY 



Ralph W. 

During the past year the study of the Shan- 
wang flora has been completed in cooperation 
with Dr. Hsen Hsu Hu, and a paper sub- 
mitted for publication. This flora from Shan- 
tung Province, China, is well represented in 
numbers both of specimens and of species. 
Unlike many Tertiary collections, it includes 
numerous fruits as well as leaf impressions. 
Fossil plants of the same age are so widely 
distributed in western North America and 
Europe that a reasonably complete picture 
may now be drawn of the character and 
distribution of forests in the northern hemi- 
sphere during the closing stages of the 
Miocene epoch. 

In the Shanwang flora there is definite evi- 
dence of a mixture of typically temperate 
trees with genera now found in regions of 
warmer climate. Similar mingling of low- 
and high-latitude genera has been noted in 
the Upper Miocene floras of western North 
America and Europe. It is still to be found 
in the Yangtse Valley, where temperate trees 
of the upper slopes range downward to the 
levels occupied by subtropical forms. Such a 



Chaney 

modern ecotone is interpreted as resulting 
from a dynamic environment. The similar 
overlapping of climatic types in Shantung 
Province and elsewhere during the Miocene 
seems also to have resulted from climatic or 
topographic instability. These Miocene eco- 
tones therefore throw light on the physical 
history of later Tertiary time, and verify our 
conclusions, drawn from other data, that this 
was an epoch of mountain-making and cli- 
matic fluctuations. The latter were all in the 
same direction on the northern continents, an 
increasing number of subtropical genera indi- 
cating rising temperature. This corroborates 
our opinion that Tertiary climatic changes 
were widespread rather than local, and that 
the positions of the continents with relation 
to the North Pole were essentially as they 
are today. 

Continuation of studies of the Tertiary 
vegetation of Oregon has centered on Pliocene 
floras from The Dalles and Troutdale. Addi- 
tional material has been collected, in cooper- 
ation with the Geological Society of America, 
which indicates a transition from the mild 



176 



CARNEGIE INSTITUTION OF WASHINGTON 



climates of earlier Tertiary time to the more 
rigorous climate of today. The disappearance 
of the redwood and its associates from the 
area east of the Cascades, and the increasing 
abundance of oak and box elder, are inter- 
preted as resulting both from world-wide 
climatic changes and from the local effects of 
the Cascade uplift. This work in Oregon is 
closely related to the studies of Dr. Axelrod 
on the Pliocene of California and Nevada. 

The geologic section in the John Day Basin 
of eastern Oregon has long been recognized 
as the most complete sequence of terrestrial 
beds in western North America. The fossil 
floras contained in these beds are abundant 
and well preserved. Discovery of closely 
related floras in bordering areas of Oregon, 
and in adjacent states in western America, 
makes possible the assignment of the rocks 
containing them to their proper levels in the 
Tertiary section. During the field season of 
1939, plant fossils have been collected in 
Harney County, south of the John Day Basin, 
in an area where little geologic or paleonto- 
logic work has been carried on. These fossils 
resemble the trees of the Mascall flora of the 
John Day Basin, a flora closely related in age 
to the Shanwang flora of China. Geologic 
studies indicate that volcanic sediments and 
lavas in this part of southern Oregon may 
closely correspond to the rock sequence of 
the John Day Basin, and suggest that other 
fossils may be found from several horizons 
which will establish a complete floral 
sequence. 

Investigations of colleagues and students 
which bear upon problems of Tertiary floral 
history may be summarized as follows: 

D. I. Axelrod. The Mulholland flora, from 
the Pliocene of west central California, has 
been studied and a report has been completed 
for publication. This flora is characterized by 
evergreen oaks, poplars, and other trees which 
are believed to have migrated northward 
from a center of origin in Mexico. Such 
typical California genera as Lyonothamnus 
and Fremontia are listed as fossils for the first 
time from this and related floras. Other 



Pliocene floras in California and Nevada have 
been collected and are being studied by Dr. 
Axelrod, who is entering his second year as 
National Research Council Fellow, with head- 
quarters at the U. S. National Museum in 
Washington. 

C. Condit. Additional collections from the 
western slopes of the Sierras give a relatively 
complete picture of the forests and environ- 
ments in this region toward the close of 
Tertiary time. Reports on the Remington 
Hill and Table Mountain floras have been 
prepared for publication. The Remington 
Hill flora, which is referred to the late Mio- 
cene, is made up largely of genera which have 
come down from the north, and which are 
widely represented in Tertiary floras else- 
where in the northern hemisphere. The Table 
Mountain flora, of early Pliocene age, con- 
tains an additional southern element, and 
approaches in composition the vegetation now 
living in the Sierra Nevada of California. 

H. D. MacGinitie. The study of the 
Chalk Bluffs has been completed, and a report 
on this subtropical forest of the California 
Eocene has been written. It shows a close 
resemblance to the vegetation of Mexico at 
middle elevations, and indicates an environ- 
ment wholly unlike that now found in the 
mountains of central California. Dr. Mac- 
Ginitie is continuing his study of the Floris- 
sant flora of the Rocky Mountains area. 

B. B. Wilder. Large collections have been 
made of a Miocene flora in northwestern 
Oregon. This work has progressed to a point 
where relations with other Oregon floras have 
been noted. 

The study of Triassic material from Ari- 
zona has been brought to completion by L. H. 
Daugherty. Numerous cycads, ferns, and 
conifers make this the largest and most sig- 
nificant flora of the Triassic age which has 
been studied in America for many years. The 
structure of several well-preserved specimens 
has received particular emphasis. A climate 
less arid than that of the Southwest today is 
indicated by this Chinle flora. 



DIVISION OF PLANT BIOLOGY 



177 



BIBLIOGRAPHY 



Abbe, Lucy B., and A. S. Crafts. Phloem of 
white pine and other coniferous species. 
Bot. Gaz., vol. 100, pp. 695-722 (1939). 

Axelrod, Daniel I. A Miocene flora from the 
western border of the Mohave Desert. 
Carnegie Inst. Wash. Pub. No. 516. ii + 
129 pp. (1939). 

Bailey, I. W. The microfibrillar and micro- 
capillary structure of the cell wall. Bull. 
Torrey Bot. Club, vol. 66, pp. 201-213 

(i939)- 
Chaney, R. W. Discrepancies between the 
chronological testimony of fossil plants and 
animals (discussion). Proc. 25th Indian 
Sci. Cong., pp. 186-187 (1939). 

Tertiary forests and continental history. 

Bull. Geol. Soc. Amer., vol. 51, pp. 469-488 
(1940). 

Clausen, Jens, David D. Keck, and William M. 
Hiesey. Experimental studies on the nature 
of species. I. Effect of varied environments 
on western North American plants. Car- 
negie Inst. Wash. Pub. No. 520. vii + 452 
pp. (1940). 

Clements, Edith S., and Frederic E. Clements. 
Flower pageant of the Midwest. Nat. Geog. 
Mag., vol. 76, pp. 219-271 (1939). 

Clements, Frederic E. See Clements, Edith S.; 
Martin, Emmett V. 

Crafts, A. S. The relation between structure 
and function of the phloem. Amer. Jour. 
Bot., vol. 26, pp. 172-177 (1939). 

See Abbe, Lucy B. 

Dice, Lee R. Variations in the cactus mouse, 
Peromyscus eremicus. Contr. Lab. Vert. 
Genetics, Univ. Mich., No. 8, pp. 1-27 

(i939)- 

An estimate of the population of deer- 
mice in the Black Hills of South Dakota and 
Wyoming. Contr. Lab. Vert. Genetics, 
Univ. Mich., No. 10, pp. 1-5 (1939). 

The Sonoran biotic province. Ecology, 



vol. 20, pp. 118-129 (1939). 

Dorf,- Erling. Relationship between floras of 
type Lance and Fort Union formations. 
Bull. Geol. Soc. Amer., vol. 51, pp. 213-236 
(1940). 

An illustrated catalogue of Mesozoic 

and early Cenozoic plants of North America. 
Science, vol. 91, p. 478 (1940). 

Emerson, Robert, and Charlton M. Lewis. Fac- 
tors influencing the efficiency of photosyn- 
thesis. Amer. Jour. Bot., vol. 26, pp. 808- 
822 (1939)- 



Hiesey, William M. Environmental influence 
and transplant experiments. Bot. Rev., 
vol. 6, pp. 181-203 ( J 94 )- 

See Clausen, Jens. 

Keck, David D. New subspecies and combina- 
tions in Penstcmon. In Kearney and Pebbles, 
Arizona plants: new species, varieties and 
combinations. Jour. Wash. Acad. Sci., vol. 
29, pp. 490-491 (1939). 

Studies in Penstemon VII. The subsec- 
tions Gairdneriani, Deusti, and Arenarii of 
the Graciles, and miscellaneous new species. 
Amer. Midland Naturalist, vol. 23, pp. 594- 
616 (1940). 

The identity of Madia dissitiflora 

(Nutt.) Torr. & Gray. Madrono, vol. 5, 
pp. 169-170 (1940). 

New subspecies in Haplopappus. Ma- 
drono, vol. 5, pp. 164-165 (1940). 

Notes on Orthocarpus. Madrono, vol. 

5, pp. 164-170 (1940). 

See Clausen, Jens. 

Lewis, Charlton M. See Emerson, Robert. 
Linderstr0m-Lang, K. See Strain, Harold H. 
MacDougal, D. T. Growth features of Quercus 

agrifolia. Trees, vol. 2, no. 2, pp. 7, 15, 18 

(i939)- 

Studies of root-systems of trees. Jour. 

New York Bot. Garden, vol. 40, pp. 45-46 
(i939)- 

Features of growth-control in trees. 



Proc. Amer. Philos. Soc, vol. 81, pp. 421- 

445 0939) • 
Mackinney, G. Criteria for the purity of chloro- 
phyll preparations. Jour. Biol. Chem., vol. 

132, pp. 91-109 (1940). 
Martin, Emmett V., and Frederic E. Clements. 

Adaptation and origin in the plant world. 

I. Factors and functions in coastal dunes. 

Carnegie Inst. Wash. Pub. No. 521. viii + 

107 pp. (1939). 
Smith, James H. C. The absorption of carbon 

dioxide by unilluminated leaves. Plant 

Physiol., vol. 15, pp. 183-224 (1940). 
Strain, Harold H. Leaf xanthophylls. Chronica 

Botanica, vol. 5, pp. 339-340 (1939). 
Extraction of proteins and proteolytic 

enzymes from yeast. Enzymologia, vol. 7, 

pp. 133-141 (1939); Compt. rend. trav. Lab. 

Carlsberg, vol. 23, pp. 149-172 (1940). 
and K. Linderstr0m-Lang. Oxygenation 

of papain digests of wool. Formation of 

compounds insoluble in trichloroacetic acid. 

Enzymologia, vol. 7, pp. 241-244 (1939). 



15 



178 



CARNEGIE INSTITUTION OF WASHINGTON 



Sykes, Godfrey. Rio Santa Cruz of Arizona; a 
paradigm desert streamway. Pan-Amer. 
Geologist, vol. 72, pp. 81-92 (1939). 

Wiggins, Ira L. Distributional notes on and a 
key to species of Cheilanthes in the Sonoran 
Desert and certain adjacent regions. Amer- 
ican Fern Journal, vol. 29, pp. 59-69 
(i939)- 



— Folklore and fact of medicinal plants 
in rural Mexico. Jour. New York Bot. 
Garden, vol. 40, pp. 176-179 (1939). 

— Taxonomic notes on the genus Dalea 
Juss. and related genera as represented in 
the Sonoran Desert. Contr. Dudley Her- 
barium, Stanford Univ., vol. 3, pp. 41-64 
(1940). 



DEPARTMENT OF EMBRYOLOGY 

Baltimore, Maryland 
GEORGE W. CORNER, Director 



The year 1939-1940 has been one of 
momentous changes in the staff of the Depart- 
ment of Embryology. Dr. George L. Streeter 
retired from the directorship on May 1, 1940, 
after twenty-six years' service, twenty-three of 
them as Director. Dr. Streeter was appointed 
a staff member on July 1, 1914, and was 
placed in charge of the Department in 19 17 
after the untimely death of Dr. Franklin P. 
Mall, founder and first Director of the labora- 
tory. Having shared intimately in the devel- 
opment of Dr. Mall's plans, Dr. Streeter was 
eminently successful in carrying on and ex- 
panding them. The Department as it now 
stands, with its unexcelled collection of 
human embryos, its broad outlook, and its 
widespread cooperative influence among the 
embryologists of the world, is a reflection of 
Dr. Streeter's talents and personality. 

The many contributions to the science of 
embryology which he has made through his 
personal researches are well known to col- 
leagues everywhere, and have been fully (if 
perhaps over modestly) reported by him in 
these Year Books. 

It is a matter of great satisfaction to all 
connected with the Department that Dr. 
Streeter is to continue his work under a grant 
from the Carnegie Corporation of New York, 
and that he is to be in the immediate neigh- 
borhood of the laboratory so that his counsel 
and encouragement will be available. 

Dr. Warren H. Lewis, Research Associate, 
who retired July 1, 1940, was appointed to 
the staff on August 1, 1919. Dr. Lewis was 
one of the pioneers in experimental embry- 
ology; his work on the factors controlling the 
development of the lens has indeed become 
a classic in that field. His major contributions 
as a member of the Carnegie Institution have 
been to the science of cytology and its appli- 
cation in the study of histology and of tumor 
growth, through the method of tissue culture. 
In this work he is recognized internationally 
as a leader. Dr. Lewis will continue his work 



as a member of the staff of the Wistar Insti- 
tute of Anatomy and Biology in Philadelphia. 
It has been arranged that Dr. Margaret R. 
Lewis will also work at the Wistar Institute, 
though remaining a Research Associate in the 
Department of Embryology. 

Dr. C. W. Metz was appointed, beginning 
July 1, 1940, Professor of Zoology in the 
University of Pennsylvania. Dr. Metz has 
been associated with the Carnegie Institution 
during his entire career, having been resident 
investigator in the Department of Genetics 
from 1914 to 1930, and Research Associate in 
the Department of Embryology from 1930 to 
1940. In his special field of cytology as ap- 
plied to genetics he has attained great dis- 
tinction, as is evidenced by his call to take 
charge of zoology at Pennsylvania. 

Mr. James F. Didusch, who was appointed 
artist on September 1, 19 13, as one of the very 
first to join the Department, was appointed 
to succeed, on September 1, 1940, his distin- 
guished teacher, Max Broedel, as head of the 
Department of Art as Applied to Medicine, 
in the Johns Hopkins Medical School. Mr. 
Didusch has brought to his tasks here not 
only superb draftsmanship, but scientific ac- 
curacy and intelligence of a high order. It is 
not too much to say that by his personal 
standard of work and his special combination 
of critical frankness with good will he has 
helped set and maintain the standards of the 
laboratory. His hundreds of beautiful and 
accurate drawings, appearing through the 
years in the "Contributions to Embryology," 
have added greatly to the value of the series. 
We are fortunate that his promotion takes 
him no farther away than the room next to 
his former studio, and thus we shall have the 
opportunity to consult with him. 

Dr. Robert K. Burns, Jr., Associate Pro- 
fessor of Anatomy in the University of 
Rochester, School of Medicine and Dentistry, 
was appointed a staff member as of July 1, 



179 



CARNEGIE INSTITUTION OF WASHINGTON 



1940. He is expected to conduct investigations 
in experimental embryology in mammals. 

Dr. Louis B. Flexner, Associate in Anatomy 
in the Johns Hopkins University, School of 
Medicine, was appointed Research Associate 



as of September 1, 1940, and expects to carry 
on studies in the physical and chemical aspects 
of embryology, making use of radioactive 
substances in cooperation with the Depart- 
ment of Terrestrial Magnetism. 



EMBRYOLOGY 



Another Early Primate Embryo 
(Chimpanzee) 

The project of comparative study of early 
embryos of the various primate species, dis- 
cussed by Dr. Streeter in previous reports, 
was continued by the acquisition and study 
of a io'/^-day embryo of the chimpanzee. 
This specimen was obtained through the 
cooperation of the Yale Laboratories of Pri- 
mate Biology, Orange Park, Florida. Pre- 
vious studies by Yerkes and Elder of that 
laboratory have made known the time of 
ovulation of the chimpanzee (i.e., about the 
21st day of the 35-day menstrual cycle). Act- 
ing upon this information, Dr. Hartman was 
enabled to operate twice each upon two 
females at the Yale Laboratories. One of 
these animals furnished in 1938 the normal 
embryo "Yerkes A" which is the subject of 
the present report, and in 1939 an atypical 
blastocyst "Yerkes B." 

Dr. Heuser's study of "Yerkes A" reveals 
in the first place a picture of implantation 
almost identical with that in man at a com- 
parable age, as known from such specimens 
as the Miller ovum and the new embryos of 
Hertig and Rock (Carnegie 7699, 7700) men- 
tioned in Year Book No. 38 and now in 
process of full study and description. The 
ovum is buried in the uterine mucosa immedi- 
ately beneath the endometrium and sur- 
rounded by an early trophoblast. The embryo 
proper is similar to the earliest human em- 
bryos and to those of the rhesus monkey of 
similar ages, but differs somewhat in the 
precocity and abundant growth of its primi- 
tive mesoblast and in the apparently late 
formation of the yolk sac. 

In Year Book No. 37 (1937-1938) Dr. 
Streeter pointed out the fact that when we 
examine progressively earlier and earlier pri- 



mate embryos we finally get back to stages 
at which they resemble other mammalian 
embryos more and more closely. At the 
earliest stages, developmental phenomena are 
in large part common to all mammals. 
Against this important fact, Dr. Heuser's 
description of the chimpanzee ovum calls our 
attention to the opposite and perhaps equally 
important point that certain differences be- 
tween closely related species can be perceived 
even at the nth day of development. Since 
we already know that the unsegmented eggs 
of various mammals are distinguishable by 
slight differences, we may suppose that the 
different species are never quite alike in their 
morphology. 

Volumetric Analysis of Young Embryos 

The rate of growth of the human organism 
as a whole has been studied quite thoroughly 
from the fetal stage on to maturity. Not only 
have changes in weight and general dimen- 
sions of the whole body been followed in this 
way, but also the weights of individual organs 
and the changes in their sizes and weights 
relative to each other and to the whole body. 
Such studies, however, have not been carried 
back into the embryonic period. Little infor- 
mation is available concerning the exact pro- 
portion of parts in embryos younger than the 
second lunar month. This lacuna is due 
partly to the inapplicability of usual methods 
of measurement to younger embryos, for 
obviously a specimen no bigger than a grain 
of millet seed, which has been sectioned and 
mounted on slides, cannot be measured and 
analyzed directly with calipers and a chemical 
balance. It is also due to a lack of suitable 
material, for it is necessary to make use of 
embryos obtained in the uterus and sectioned 
in situ, in order to obtain the volume of an 



DEPARTMENT OF EMBRYOLOGY 



181 



embryo and its parts in terms of the fetal 
membranes that support it. 

Dr. E. A. Boyden, of the University of 
Minnesota, having readily available a 12- 
somite embryo of suitable character (the 
Litzenberg embryo), has undertaken a volu- 
metric analysis. The basic method of the 
study was Hammar's paper-weight method, 
by which sections of the embryo are magni- 
fied and projected optically onto paper of 
uniform thickness. The desired regions or 
organs are traced and the traced areas cut out 
and weighed. To this laborious method Dr. 
Boyden has applied much ingenuity of analy- 
sis and comparison. Since the Litzenberg 
embryo lacks the yolk sac and is injured in 
the mid-gut region, Boyden has supplemented 
it with a similar study of the 10-somite Corner 
embryo, a specimen which is relatively per- 
fect internally and well preserved, but was 
not sectioned in situ and hence lacks the 
fetal membranes. 

These two specimens, incidentally, illus- 
trate the value of the policy of broad cooper- 
ation which has characterized Dr. Streeter's 
directorship of this laboratory, for both of 
them were obtained by investigators in other 
cities, but both were studied (the Corner 
embryo in particular) in consultation with 
the Department and with the aid of its 
technical staff, and both were depicted by 
Mr. Didusch. 

The two specimens represent about one day 
of development (approximately the 23d day). 
Among the findings of general interest the 
following may be cited: 

1. The trophoblast of the Litzenberg em- 
bryo is 380 times the tissue of the embryo; 
the intervillous space, 640 times. The actual 
surface of the villi (through which nutritive 
substances pass from mother to embryo), 
computed on the basis of a membrane 20 
microns thick, would cover an area about 
2 m. square, giving an area of 12,340 sq. mm. 
for every cubic millimeter of embryo. The 
relation, similarly expressed, of placental sur- 
face to fetal weight at term has been esti- 
mated at about 3:1 to 6:1. 

2. As further indication of the great 
amount of accessory tissues required to sup- 



port and nourish the embryo during its early 
period of rapid relative growth, we learn 
from Boyden that while the absolute volume 
of the Litzenberg embryo (deducting all 
cavities) is 0.2 cu. mm., the implantation 
cavity (combined chorionic vesicle and inter- 
villous space) is 295 cu. mm., i.e., 1300 times 
the embryo proper, 1400 times the tissue of 
the embryo, and 675 times the embryo and 
its contiguous membranes (yolk sac, amnion, 
and umbilical cord). 

3. The contractile myocardium of the 
Litzenberg embryo forms 1/19 of the tissues 
of the embryo, but only 1/13,800 of the fetal 
tissues which are to be supplied with blood 
(i.e., embryo, body stalk, yolk-sac wall, 
amnion, and chorion). This is an extremely 
low proportion of heart tissue to tissues sup- 
plied with blood (in the adult human body 
the heart is required to supply only 200 times 
its own weight) and can only be explained 
on the assumption that at this early stage, 
when the blood is just beginning to circulate, 
the fetal membranes are getting much of their 
nutrient material and carrying on their 
respiratory gas exchange and their metabolic 
excretion processes by direct diffusion to and 
from the body fluids. 

4. The brain is 1/13 (Corner embryo) to 
1/10 (Litzenberg embryo) of the tissues of 
the embryo. At birth the ratio is 1:10 to 1:8, 
and in the adult 1:42 (males) and 1:40 
(females). 

5. In the Litzenberg embryo the brain is 
larger in proportion to the whole body than 
in the slightly younger Corner specimen, 
whereas the ratio of spinal cord to body is 
the same. This hints that even as early as 
the 4th week the brain is growing faster than 
the spinal cord. 

Development of the Adrenal Cortex 
in Man 

Dr. Unto U. Uotila, Rockefeller Fellow in 
the Department of Anatomy at Harvard 
Medical School, has reinvestigated the de- 
velopment of the adrenal cortex in man. For 
this purpose he visited the laboratory of the 
Department of Embryology, where 36 human 



l82 



CARNEGIE INSTITUTION OF WASHINGTON 



and 3 monkey embryos were put at his dis- 
posal. His observations agree in the first place 
with the generally accepted theory regarding 
the origin of the primordial fetal adrenal 
cortex from proliferating coelomic meso- 
thelium. There has been a difference of 
opinion as to the subsequent differentiation 
of the permanent cortex. Dr. Uotila's find- 
ings confirm the view that the permanent 
cortex does not arise from the fetal cortex, 
but comes from a second proliferation of 
mesothelial cells which occurs at the age of 
6 to 6/4 weeks. The new elements come into 
contact with the ventral surface of the fetal 
cortex, where there is no investing capsule, 
and spread over the surface of the gland. The 
cells of the fetal and permanent cortex are 
cytologically distinct from the time of their 
earliest differentiation. 

Development of Gonad, Adrenal Cortex, 
and mtjllerian duct in the alligator 

Dr. Thomas R. Forbes, of the Department 
of Anatomy of the Johns Hopkins University, 
has continued his studies of the reproductive 
system of Alligator mississipiensis. The de- 
velopment of the gonads before hatching 
agrees in general with that in other reptiles. 
The alligator, like the turtle, differs from 



higher vertebrates in that the embryonic 
gonad retains for a relatively long time the 
bisexual traits characteristic of early embryos; 
that is, until late stages the cortex and medulla 
are both present and well defined. Dr. Forbes 
finds further evidences of bisexuality in juve- 
nile stages, namely the retention by immature 
females of Wolffian ducts and testis-like 
medullary tissue, and the persistence in imma- 
ture males of cortical areas and Miillerian 
duct segments. 

In the embryos and young post-hatching 
stages studied by Dr. Forbes no interstitial 
tissue was found in the testis. Whether this 
is a permanent condition must be settled by 
study of the testes of adult alligators. The 
occurrence of interstitial tissue in the reptilian 
testis seems to vary greatly from species to 
species. 

The primitive adrenal cortex is derived 
from the coelomic epithelium in continuity 
with the primordial genital gland. The two 
proliferations, of the adrenal and the gonad, 
begin at the same time and have a marked 
histological resemblance. This fact is impor- 
tant in connection with the chemical resem- 
blance of the adrenal hormone to those of 
the gonads and the widely accepted view that 
under certain conditions the adrenal cortex 
can produce androgenic hormone. 



PLACENTATION AND PLACENTAL FUNCTION 



Permeability of the Placenta 

It is hardly necessary to point out the 
importance for embryology of understanding 
the mechanism of transfer of substances across 
the placenta from the blood of the mother to 
that of the embryo and vice versa. Dr. Louis 
B. Flexner, in collaboration with Dr. Richard 
B. Roberts, has begun to investigate the possi- 
bility of studying placental permeability by 
use of radioactive isotopes ("tracer ele- 
ments"). In particular, the first experiments 
were planned to test the possibility that dif- 
ferences in size of litter mates are dependent 
upon differences in the rate of passage of 
substances from the maternal blood to the 
fetus. Radioactive sodium was therefore used 



to measure the permeability of the placentas 
of different members of a litter, the relative 
rates of transfer of the salt being then com- 
pared with the mass of the individual litter 
mates. 

Radioactive sodium (Na 24 ) was prepared 
in the form of sodium chloride by use of the 
electrostatic pressure generator of the Depart- 
ment of Terrestrial Magnetism. It was dis- 
solved in water and injected into the blood 
stream of the pregnant cat. The fetuses 
(removed under anesthesia at a suitable time 
after the injection) and blood samples from 
the mother having been ashed, the radio- 
activity of the ashed remains was measured 
with a pressure ionization chamber. Five 



DEPARTMENT OF EMBRYOLOGY 



l8 3 



litters were studied. The resulting figures 
show a fairly high inverse correlation between 
total fetal mass and content of radioactive 
sodium per unit weight; that is, each fetus of 
a litter, whether large or small, has received 
through the placenta approximately the same 
absolute amount of the tracer salt. So far 
as can be judged from this study made during 



the last 4 days of gestation, weight of the 
fetus is not related to difference in permea- 
bility of the placenta to sodium chloride. 

More important even than this particular 
finding is the demonstration of usefulness 
and practicability of the radioactive tracer 
elements. Dr. Flexner is continuing their use 
in similar problems. 



PHYSIOLOGY OF THE REPRODUCTIVE SYSTEM 



In a symposium at the December 1939 
meeting of the American Association of 
Anatomists Dr. Hartman presented a survey 
of the studies on the physiology of reproduc- 
tion in the monkey which have been carried 
on by himself and associates for many years. 
The great additions to our knowledge won 
for us by this work have all been reported 
by Dr. Streeter in the successive Year Books, 
and need not be repeated here; but Dr. Hart- 
man's resume calls attention very forcefully 
not only to what has been gained already, 
but also to the possibilities of further advance 
in understanding of human reproduction 
through continued study of the monkeys and 
anthropoid apes. 

Breeding Season of the Muskrat 

Dr. Thomas R. Forbes, in collaboration 
with Dr. R. K. Enders, of Swarthmore Col- 
lege, has made a study (under the auspices 
of the U. S. Biological Service) of the time 
of the breeding season of the muskrat. This 
has not been well understood and probably 
varies in different parts of the United States. 
Examination of the ovaries of 119 muskrats, 
trapped from November through March at 
the Blackwater Migratory Bird Refuge on the 
Eastern Shore of Maryland, revealed evi- 
dences of ovulation (i.e., the presence of re- 
cent corpora lutea) in January, February, and 
March. By comparison of histological ap- 
pearances, Forbes and Enders came to the 
conclusion that the first ovulatory cycle of 
the annual breeding period occurred during 
the early part of February and the middle 
of March, and that a second ovulatory cycle 
subsequently appeared. Such studies, though 
primarily of importance to breeders of fur- 



bearing animals, add also to our accumulat- 
ing general knowledge of reproduction in 
mammals. 

Menstruation in Intraocular Transplants 
of the Endometrium 

In Year Book No. 37 reference was made 
to the work of Dr. J. E. Markee, whose 
studies on menstruation, made chiefly at Stan- 
ford University, were carried on in our 
laboratory during the year 1935— 1936. Al- 
though Dr. Markee had kept his colleagues 
aware of the general nature of his work by 
reports at scientific meetings, there was no 
comprehensive account previous to the mono- 
graph which appears in the current "Contri- 
butions to Embryology." 

Dr. Markee has utilized a new method 
of studying the phenomenon of menstruation 
by implanting small pieces of the lining of 
the uterus (endometrium) into the anterior 
chamber of the eye. Here they take root, are 
nourished by blood vessels which grow into 
them from the iris, and can be observed with 
moderate powers of the microscope, through 
the transparent cornea. In such grafts, men- 
strual bleeding occurs much as it does in 
the uterus and follows the same cycle. As in 
the uterus, so in the intraocular grafts the 
endometrium goes through a cycle of alter- 
nating growth and regression. Markee finds 
that when regression is rapid, it is followed 
by menstrual bleeding. In this process the 
coiled arteries of the endometrium are espe- 
cially involved; as the transplants diminish in 
the phase of retrogression, there is first a 
period of stasis of blood in the region supplied 
by the coiled arteries, and then a period of 
constriction of the arteries. The tissue which 



184 



CARNEGIE INSTITUTION OF WASHINGTON 



they supply is thus left bloodless for several 
hours. The arteries then relax, the blood flow 
is resumed, and blood escapes from the 
arterioles, capillaries, or veins. The small 
quantities of blood thus freed into the tissue 
escape from the grafts in various ways, de- 
scribed in detail by Markee. 

An important conclusion from these obser- 
vations is that the process is much the same 
in anovulatory as in ovulatory menstruation. 

Dr. Markee did a good many experiments 
with the ovarian hormones estrone and pro- 
gesterone, and with the male hormones andro- 
sterone and testosterone, especially during his 
year in Baltimore, when he had the active 
cooperation of Dr. Hartman. Among his 
many findings we may note the following. 
A course of estrone, sharply discontinued 
(causing a state of estrone deprivation), gave 
rise to menstruation-like bleeding in the 
grafts, as we should expect from previous 
experiments. By gradual withdrawal of 
estrone, however, it was possible to induce 
slow retrogression of the endometrium, as 
verified by direct observation of the grafts. 
Menstruation then did not occur. Menstru- 
ation which occurred during and in spite of 
ample daily injections of estrone was preceded 
by regression of the endometrium. The injec- 
tion of estrone during menstruation did not 
alter the sequence of events. The bleeding 
produced by estrone deprivation and pro- 
gesterone deprivation is similar to normal 
menstruation, a very important point for the 
theory of menstruation. 

By inserting crystalline estrone into an eye 
in which a graft was present, and by subse- 
quent removal of the hormone, it was possible 
in a series of experiments either to raise or to 
lower at will the concentration of estrone 
acting locally upon the graft in the same eye 
relative to that acting on a graft in the other 
eye via the general blood stream. The results 
showed that the rate of regression of the graft, 
and the occurrence or nonoccurrence of bleed- 
ing, are under control of hormone acting 
locally (i.e., directly) on the graft. 

Dr. Markee concludes that in all proba- 
bility menstrual bleeding is the result of 



rapid regression of the endometrium and the 
immediate cause of the bleeding must be 
looked for within the frame of that process. 

Progesterone Not Excreted as Pregnan- 
diol in the Monkey 

The discovery about three years ago by 
Venning and Browne, of Montreal, that in 
the human female the corpus luteum hor- 
mone, progesterone, is excreted as pregnan- 
diol, conjugated with glycuronic acid, has 
already been of great value in studies of 
corpus luteum function in the menstrual cycle 
and in pregnancy, both normal and ab- 
normal. By measuring the amount of preg- 
nandiol glycuronidate in the urine, at least 
a rough determination of the activity of the 
corpus luteum may be obtained. Inasmuch 
as the rhesus monkey has come to be the 
standard primate animal for the study of 
menstrual phenomena and of pregnancy, 
there have been several attempts, published 
and unpublished, to identify pregnanediol in 
monkey urine. These have yielded negative 
results. 

Dr. Carl G. Hartman therefore joined 
forces with a biochemist of great experience 
with the steroidal hormones, Professor R. E. 
Marker, of Pennsylvania State College, to 
obtain a more complete assay of pregnancy 
urine of the monkey for various steroidal 
compounds. Professor Marker was supplied 
first with 12 gallons of urine from 3 pregnant 
animals. The assays showed no trace of the 
pregnanediols common to pregnancy urines 
of several other species including man. When 
progesterone was administered to a pregnant 
monkey in a large amount (more than 1 g. 
in 20 days) pregnanediols did not appear in 
the urine. The progesterone had no unfavor- 
able effect on either the mother or the fetus. 

We remain therefore in ignorance as to the 
steps by which progesterone is metabolized in 
the monkey, and as to the nature of its excre- 
tionary end products. 

A pregnant monkey which received more 
than 1 g. of estrone in 20 days (which caused 
the death of the fetus) yielded only a very 
small portion of the total estrone injected. 






DEPARTMENT OF EMBRYOLOGY 



l8 5 



Effect of Testosterone upon the 
Uterus of the Monkey 

Dr. C. G. Hartman has reported his experi- 
ences with the administration of steroidal 
hormones in pellets inserted under the skin 
by the method devised by Deanesly. The 
method is especially useful when the effects 
of small amounts of hormone over long 
periods of time are desired. Hartman reports 
physiological effects in a monkey during 4 
months from a single 3-mg. pellet of estrone. 

Eighteen experiments were performed to 
determine the effect of the male hormone 
testosterone upon the monkey's endometrium. 
In general, testosterone did not exert an 
action resembling that of progesterone; a 
progestational endometrium, with serrated 
secretory glands, was never attained with 
testosterone alone or in combination with 
estrogens. On the other hand, no evidence 
was found for any antagonistic action of 
testosterone against either estrogen or pro- 
gesterone when concomitantly injected with 
one or both of these hormones. Testosterone, 
however, reddens the sex skin like an estrogen 
and is able to maintain an endometrium al- 
ready built up by an estrogen. 

Among the well known effects of the cor- 
pus luteum hormone is that of inhibiting the 
menstruation-like bleeding which follows 
withdrawal of estrogens. The male hormone 
testosterone and its acetic and propionic esters 
produce the same effect. Dr. A. R. Abarbanel 
finds that a similar action is exerted by injec- 
tion of the dipropionic ester and also by 
methyl-testosterone and ethinyl-testosterone 
(pregneninolone), and reports partial success 
in eliciting the same action when testosterone 
propionate (given with bile salts) and methyl- 
and ethinyl-testosterone were given by mouth. 
The latter drug has already appeared in the 
drug trade as a substance having progesterone- 
like action (as determined by another test) 
when given by mouth. In Dr. Abarbanel's 
experiments it prevented estrin-deprivation 
bleeding when given by injection in doses of 
5 mg. daily. By mouth, it delayed but did 
not prevent bleeding in doses of 20 mg. daily. 
As judged by this result, ethinyl-testosterone 



is not a very effective or economical oral sub- 
stitute for progesterone. 

Gonadal Hormones in Reptiles 

Dr. T. R. Forbes has continued his observa- 
tions on the effects of gonadal hormones in 
reptiles, studying a number of young alliga- 
tors which received injections of the male 
hormone testosterone propionate. The ovi- 
ducts of the injected females showed a uni- 
form and marked development and growth, 
and the phallic organs of both sexes (penes 
and clitorides) were strikingly hypertrophic. 
The mesonephroi and mesonephric ducts 
were not affected in either sex. Histological 
findings suggested some influence of the hor- 
mone on the gonads, but the evidence was not 
conclusive. 

Adult male lizards of the genus Sceleporus 
reacted vigorously to the implantation of pel- 
lets of testosterone and of estrone. The male 
hormone caused hypertrophy of the male ac- 
cessory organs and stimulated spermato- 
genesis. Estrone prevented spermatogenesis, 
caused atrophy of the testes, and reduced the 
size of the epididymides. 

Stimulation of Cell Division in Male 
Organs by Estrogens 

It is well known that the estrogens or so- 
called female sex hormones produce effects on 
the male reproductive system, inducing, for 
example, changes in the epithelium and in- 
crease of the fibromuscular stroma of the 
prostate gland. After longer treatment similar 
effects are produced in the seminal vesicles 
and the more distal parts of the genitourinary 
canal. There is some evidence that mitotic 
division, presumably induced by direct action 
of the hormone, is a factor in producing the 
epithelial changes, but the hyperplastic fibro- 
muscular stroma of the prostate has not as 
yet been observed to contain mitotic divisions. 
Mr. Richard Tislowitz, of the Johns Hopkins 
Medical School, at Dr. Hartman's suggestion 
has applied to this problem the colchicine 
technique by which mitotic divisions are 
arrested and accumulated. Mitotic figures 
were readily found in the fibromuscular 



i86 



CARNEGIE INSTITUTION OF WASHINGTON 



stroma. An artificial estrogen, diethyl-stilbo- 
estrol, produced changes in the prostate and 
seminal vesicles similar to those induced by 
estrogens of steroid structure. 

Penetrability of Mucus in the Cervix 
Uteri by Spermatozoa 

Recent studies have indicated that the 
mucus of the human uterine cervix, through 
which spermatozoa must pass in order to fer- 
tilize the ovum, may vary in its penetrability, 
and even that such a variation may occur 
normally as a feature of the female reproduc- 
tive cycle. Dr. J. K. Lamar, working in the 
Department as a fellow of the National Com- 
mittee on Maternal Health in collaboration 
with two workers in the Department of Ob- 
stetrics of the Johns Hopkins University, 
namely L. B. Shettles (on a similar fellow- 
ship) and Eleanor Delfs (a fellow of E. R. 
Squibb and Sons), has applied to this prob- 
lem a simple and satisfactory method devised 
by himself, in which the passage of sper- 
matozoa through a sample of mucus in a 
capillary glass tube is watched and timed 
under the microscope. The results confirmed 
the statement, made by Seguy and Vimeux in 
1933, that there is a cyclic production of a 
special type of cervical mucus at about mid- 
cycle, which renders the cervix temporarily 
penetrable by spermatozoa. The spread of 
this phase in the cycle is roughly from day 
9 through day 19, although for any one cycle 
the period of penetrability may be restricted 
to about 4 days. This period coincides 
with the period of lowest number of leuco- 
cytes in the mucus, of the highest pH (disre- 
garding the period of menstrual flow), the 
largest amount of mucus secreted, and the 
height of conditions favoring longevity of 
spermatozoa in the mucus. The relation be- 
tween penetrability and viscosity of the mucus 
is not clear. 

Indications are that the menstrual dis- 
charge is penetrable by spermatozoa, but the 
mucus of the phase between menstruation 
and the mid-cycle is relatively impenetrable, 



and that of the phase between mid-cycle and 
the subsequent menstruation is quite impene- 
trable. The authors urge the application of 
the microtube method, and the facts they 
have ascertained with it, to the investigation 
of otherwise unexplained cases of sterility. 

Hormones and Mating Behavior 

Following up a study of sex behavior of 
rats under stimulation with estrogenic hor- 
mones, reported in Year Book No. 37, Dr. 
Josephine Ball observed the sex behavior of 
male rats castrated at weaning and treated 
with estrogens during the following i l /i to 
3 months, and compared it with that of simi- 
larly treated female litter mates and of normal 
brothers and sisters. All the castrates, male 
and female, showed part of the typical female 
estrous behavior (copulatory lordosis), but the 
rest of the pattern was seldom elicited, never 
in males. Four of six male castrates copulated 
like males to a limited extent. None of the 
females showed any masculine tendencies. 

The experiment suggests that the neuro- 
muscular pattern underlying male copulatory 
behavior is organized very early, possibly even 
before birth, and that the hormones of puberty 
act by lowering the threshold of this activity, 
not by organizing it. 

Dr. Ball has also investigated the effect of 
the male hormone testosterone on the sex be- 
havior of young adult female rats. After 
fairly large doses during 2 months, eight to 
ten rats continued to accept the males even 
though signs of the female cycle were re- 
pressed. At the same time the treated female 
rats also exhibited male sex behavior to a 
considerable degree. Untreated females ex- 
hibit male copulatory behavior under the in- 
fluence of certain special stimuli. It is con- 
cluded that the male copulatory pattern in 
more or less rudimentary form is part of the 
equipment of the normal female rat. The 
threshold of this behavior pattern is normally 
very high but it can be lowered by treatment 
with the male hormone. 



DEPARTMENT OF EMBRYOLOGY 



187 



ENDOCRINE ORGANS 



Activity of the Adrenal Cortex 

We are greatly in need of methods by 
which the physiological activity of glands of 
internal secretion can be related to the struc- 
ture of these glands as seen under the micro- 
scope. Dr. Louis B. Flexner, in collaboration 
with Dr. Arthur Grollman, of the Depart- 
ment of Pharmacology of the Johns Hopkins 
Medical School, has studied the adrenal cortex 
of the rat, making use of the fact that the 
cortical cells contain substances which reduce 
osmium tetroxide and thus give visible evi- 
dence of their activity by black deposits of the 
lower oxides of osmium. Dr. Flexner and Dr. 
Grollman have subjected rats to experimental 
conditions known to depress or to stimulate 
the physiological activity of the adrenal gland. 
If, for example, the animals are supplied with 
cortical hormone by injection, these glands 
are not called on to produce as much hor- 
mone as normally. In this circumstance the 
investigators found a diminished reduction 
of osmium tetroxide in the adrenal cortex. 
When, on the other hand, the output of corti- 
cal hormone was stimulated by subjecting the 
rats to extremes of temperature, or when one 
adrenal was made to secrete more actively by 
removing the other, Dr. Flexner and Dr. 
Grollman found an increased reduction of 
osmium tetroxide by the cells of the adrenal 
cortex. Increased reduction was also pro- 
duced by inanition and by the injection of 
tetrahydro-/?-naphthylamine, which is a sym- 
pathetic stimulant, and by the thyrotropic 
hormone of the pituitary gland. 

The changes in reducing power of the cells 
thus produced are not to be taken as a direct 
measure of the presence or quantity of cortical 
hormone, but rather, no doubt, as evidence 
of altered metabolic states associated with 
endocrine activity. The reducing substances 
are of several kinds, including unsaturated 
lipids, various steroids including the cortical 
hormone, and compounds such as ascorbic 
acid and glutathione. 

The authors point out that their results can- 
not as yet be transferred to other species; in 



studying the rat they have had the advantage 
of a highly standardized species. 

X-ZONE OF THE ADRENAL 

One of the many puzzling questions af- 
forded by the adrenal gland is that of the 
nature and function of the so-called X-zone 
of the adrenal cortex. This occurs in mice, 
and has not been clearly identified in other 
mammals. It is a zone of cells at the inner 
side of the cortex, between the zona fasci- 
culata and the medulla. First recognizable in 
the second week of intra-uterine life, it soon 
degenerates in the male, but in the unmated 
female persists throughout the reproductive 
period. During pregnancy it degenerates. 
Dr. I. Gersh of the Department of Anatomy 
and Dr. A. Grollman of the Department of 
Pharmacology of the Johns Hopkins Medical 
School, following up certain older observa- 
tions, find that when the immature or castrate 
mouse is given thyroid powder, and thus 
caused to need adrenal cortical hormone, 
there is a pronounced hypertrophy of the 
X-zone. Administration of cortical hormone, 
on the contrary, causes degeneration of the 
X-zone, and large doses given to very young 
animals may inhibit its appearance. It has 
been observed that in animals which do not 
have an X-zone similar effects occur in true 
cortical tissue. The interpretation is that the 
X-zone performs the same function as the 
other cortical zones of the adrenal, and that 
the X-zone acts as a reserve tissue which can 
be called out in case of need for more cortical 
hormone, but subsides when the need does 
not exist or is satisfied in some other way. 

Protein and Iodine in Thyroid Tissues 

At the 1940 meeting of the American As- 
sociation of Anatomists, Dr. Gersh described 
his studies of the thyroid gland by application 
of the ultraviolet microscope to frozen-dried 
sections. It was possible to determine the 
concentrations, in colloid, cytoplasm, and 
nuclei, of thyroglobulin, protein-bound iodine, 
and cyclic components of protein (tyrosine 
plus tryptophane). The conclusions will be 
reviewed in a subsequent Year Book. 



CARNEGIE INSTITUTION OF WASHINGTON 



TISSUE CULTURE AND TUMOR STUDIES 



As a participant in a symposium of the 
Association for the Study of Growth, Dr. 
Warren H. Lewis has reviewed some of the 
contributions of the tissue-culture method to 
the study of development and growth. Al- 
though he was able to refer to important addi- 
tions to our knowledge of cell types and cell 
behavior, many of them achieved by himself 
and his co-workers, Dr. Lewis makes it clear 
that with respect to the broad field of growth 
and differentiation we can claim only that the 
study of tissue cultures has helped to define 
the problems. In the long run we shall need 
to attack them with a combination of morpho- 
logical methods and organic and physical 
chemistry. In this phase of progress the tech- 
niques of tissue culture will doubtless be 
highly useful. 

The Chromosomal Nature of Nucleoli 

It has become known during the past 
decade that the nucleoli of animal cells are 
in certain lower animals associated with defi- 
nite regions of particular chromosomes. Dr. 
W. H. Lewis has examined his motion pic- 
tures of normal dividing rat fibroblasts in 
tissue cultures to see whether in these mam- 
malian cells there is any sign of a similar 
relation. Dr. Lewis finds that when in the 
process of mitotic division the chromosomes 
are just attaining their maximum visibility 
and number, each of the larger nucleolar 
masses splits into two or more bodies of the 
same size and appearance as the chromo- 
somes. The smaller nucleoli remain unbroken 
and assume the appearance of chromosomes. 
When chromosomal movements begin, lead- 
ing up to their arrangement on the metaphase 
plate, it becomes impossible to follow any 
longer the separate fate of those chromosomes 
that came, or seemed to come, from the 
nucleoli. After formation of the daughter 
cells some of the chromosomal particles per- 
sist as nucleoli. Dr. Lewis concludes that in 
rat fibroblasts the nucleoli consist of chromo- 
some material. 

Dr. Lewis exhibited some of his motion 
pictures of dividing fibroblasts, upon which 



the above observations are based, at the 1940 
meeting of the American Association of 
Anatomists. The pictures indicate that the 
mechanics of cell division involves a series of 
changes in viscosity of the superficial plas- 
magel layer. 

Tissue Culture of Ovarian Epithelium 

Although ovarian tissues have been culti- 
vated in vitro, the germinal epithelium has 
not been grown. Dr. J. Herman Long, using 
the technical procedures developed by Dr. 
W. H. Lewis, Dr. M. R. Lewis, and Dr. G. O. 
Gey, has now obtained and photographed an 
abundant growth of germinal epithelium 
from the ovary of the mouse in roller-tube 
culture. The most important feature of the 
observations was the appearance of primordial 
follicles and of ova in the layer of newly 
formed epithelial cells. The ova grew to a 
size comparable with that of similar cells aris- 
ing naturally in the ovary. The observation 
has an important bearing on the question as 
to whether, in the normal mammalian ovary, 
ova are formed after birth. The mouse is the 
animal in which such neoformation of ova 
has been most plausibly described. Culture 
of the germinal epithelium of other species 
is much to be desired. 

Muscle Cells in Dibenzanthracene 
Mouse Sarcomas 

The injection of dibenzanthracene into 
mice gives rise to malignant tumors originat- 
ing from connective tissues. Dr. Warren H. 
Lewis has studied the histology of 50 such 
sarcomatous tumors in pure-strain mice. The 
point of greatest interest is that 22 of the 
tumors contained modified skeletal muscle 
fibers, muscle giant cells, and myoblasts. 
Some of them had so much muscle that they 
would probably be diagnosed as rhabdomyo- 
sarcomas. As the tumors were carried on by 
transplantations to other mice, the muscle 
cells grew less and less in number until in 
later generations they disappeared. The 
changes of the muscle cells and their deriva- 



DEPARTMENT OF EMBRYOLOGY 



189 



tives seem to be those of dedifferentiation. 
These observations offer a suggestion as to 
the nature of human malignant tumors con- 
taining muscle cells or myoblasts (rhabdo- 
myosarcomas and myoblastomas). Dr. Lewis 
points out that in these tumors, as in those of 
the experimental mouse, the muscle elements 
are probably in process of dedifferentiation 
into myoblasts and spindle cells. The large 
percentage of such tumors produced in rats 
and mice by carcinogenic agents, as compared 
with those occurring spontaneously in man, 
may be explained by the longer duration of 
the latter, giving an opportunity for any 
modified muscle originally present to de- 
generate into spindle cells. The great varia- 
tions in the histology of rhabdomyosarcomas 
and rhabdomyoblastomas, both human and 
animal, can likewise be attributed to the 
changing character of the muscle elements. 

Biological Differences in Induced 
Sarcomas 

A study of the transplantability of sarcoma- 
tous tumors induced by dibenzanthracene, 
made by Dr. M. R. Lewis and Mrs. E. G. 
Lichtenstein, was reported in Year Book No. 
37. In continuation of this study, the investi- 
gators have found six ■ spindle-cell sarcomas 
that had an inherent power to grow when 
transplanted into mice of pure inbred strains 
other than those in which the tumor origi- 
nated. The six tumors all looked alike under 
the microscope, and grew alike in mice of 
their own strain; but when transplanted into 
alien strains they exhibited striking differences 
in growth energy. Another means of observ- 
ing differences between the tumors was af- 
forded by the fact that when implanted in 
mice of alien strains they did not grow 
sufficiently to kill the host mice, but regressed. 
The mice in which a sarcoma had grown and 
regressed proved to have become resistant to 
another tumor graft of that tumor but not 
necessarily to the other five tumors. The 
existence and persistence of such pronounced 
differences between tumors of similar patho- 
logical type, presumably originating from 
similar tissues as the result of an identical 
stimulus, is quite remarkable. 



Metabolism of Sarcoma Cells in 
Tissue Culture 

Because of the unrestrained growth of cells 
of malignant tumors, a great deal of interest 
attaches to their metabolism and there have 
been many efforts to determine the extent to 
which their respiration and consumption of 
foodstuffs differ from similar activities of 
normal cells. Slices of tumor material have 
generally been used for such studies. Dr. 
C. L. Gemmill and Mr. R. Austrian, of the 
Johns Hopkins Medical School, and Dr. G. O. 
Gey have now devised means by which cells 
growing in tissue culture may readily be 
studied in the same way. By the roller-tube 
culture method an adequate amount of ma- 
terial is made available, and this is observed 
in a specially designed metabolism chamber 
provided with an all-glass pump. 

An investigation has been made of the 
oxygen consumption, utilization of glucose, 
lactate production, and metabolism of urea 
and nonprotein nitrogen of a well-known 
pure strain of malignant cells (Walker rat 
sarcoma 319). This tumor grows fairly 
rapidly in culture; the explants doubled their 
volume in about 40 days. The oxygen con- 
sumption averaged 4.5 cu. mm. per milligram 
of tissue per hour. There was no evidence of 
accumulation of lactate in the culture 
medium, an observation which does not agree 
with the generalization made on the basis of 
Warburg's work, that tumor tissue character- 
istically has deficient respiration, so that inter- 
mediate metabolites are not oxidized and lac- 
tate accumulates. The Walker sarcoma 319 
may therefore be added to the list of tumors 
which do not have a high aerobic glycolysis. 

The utilization of glucose by the cultures 
is very rapid, so rapid indeed as to indicate 
that glucose is used for other purposes besides 
oxidation. Since there is no lactate formation, 
the glucose may be stored. The nonprotein 
nitrogen in the culture medium increased 
after contact with the tumor cells. Urea did 
not increase, and in all probability the change 
in nonprotein nitrogen was due to accumula- 
tion of ammonia or amino acids produced by 
digestion of the proteins in the culture 
medium by the cells. 



190 



CARNEGIE INSTITUTION OF WASHINGTON 



Differentiation of Myeloblasts from 
Lymphoblasts 

At the very heart of our current uncertain- 
ties as to the relationship of the blood- and 
blood-forming cells lies the question of the 
identity or nonidentity of the lymphoblasts 
and myeloblasts, large immature cells with 
basophilic nongranular cytoplasm which are 
found in the bone marrow and the lymphoid 
tissue, and from which (in these respective 
situations) the granular leucocytes and the 
lymphocytes develop. In fixed and stained 
preparations these two cells look so much 
alike that workers of one school believe them 
identical, while others believe that they may 
be distinguished from each other by slight 
differences of structure, admittedly difficult 
to detect. Dr. Margaret R. Lewis, with Dr. 
A. R. Rich of the Department of Pathology 
and Dr. M. M. Wintrobe of the Department 
of Medicine of the Johns Hopkins Medical 
School, has studied these cells in hanging- 
drop tissue cultures and has recorded their 
movement in motion pictures. Myeloblasts 
were obtained from normal marrow and from 
leukemic blood, and lymphoblasts from nor- 
mal lymph nodes and from leukemic blood. 
A striking difference in the manner of loco- 
motion was revealed. In such cultures cells 
of both types move freely. The lymphoblasts 
proceed steadily, retaining a persistent broad 
anterior end which bears a few pseudopodia, 
and a rigid tail-like process at the rear. The 
cell has therefore a characteristic outline re- 
sembling a hand mirror. The picture is 
similar to that of the lymphocyte, as described 
earlier by Dr. W. H. Lewis. The myeloblasts, 
on the other hand, assume the form of a 
twisted cylinder and move in a writhing, 
wormlike manner. The leading and follow- 
ing ends of the cell remain fixed for con- 
siderable periods of time, but the direction 
of motion may be suddenly reversed. The 
leading end bears a few pseudopodia. Mono- 
cytes show the characteristic large pseudo- 
podia bordered by undulating membranes, 



which the motion pictures of W. H. Lewis 
have made familiar. M. R. Lewis, Rich, and 
Wintrobe regard their findings as evidence 
against the view that lymphoblasts and myelo- 
blasts are identical. 

The authors have also applied the same 
method to large mononuclear cells which 
appear in great numbers in the spleen when 
it is enlarged during infection — the so-called 
acute splenic tumor cells. They find that in 
tissue cultures these cells exhibit the type of 
motion characteristic of the lymphoblast, and 
conclude that they are lymphoid in character. 
It was found incidentally that infection is not 
necessary for the production of acute splenic 
tumor, for the same condition may be pro- 
duced by injection of foreign proteins. A 
lymph node draining infected tissues or a 
region into which foreign protein has been 
injected exhibits lymphoid cell proliferation 
like that characteristic of splenic tumor. It 
appears, therefore, that the lymphocyte is in 
some way functionally concerned with the 
reaction of the body to foreign protein. 

Virus of Lymphopathia Venereum 

Dr. Gey, with Dr. F. B. Bang, of the Johns 
Hopkins Department of Pathology, has been 
able to infect tissue cultures of human fibro- 
blasts with the virus of lymphopathia ve- 
nereum. The investigators have been able to 
follow in the living cells the development of 
the peculiar intracellular vesicles containing 
granular corpuscles which are characteristic 
of tissues infected with this disease. They 
found that under conditions not clearly under- 
stood the vesicular reaction of the cells may 
disappear completely, yet the virus persists in 
the tissue culture. Because of reports con- 
cerning the efficacy of sulfanilamide in the 
treatment of this infection, the drug was 
added, in low concentration, to the culture 
medium. The vesicles disappeared, but the 
experiment was not conclusive as to the effect 
on virulence. 



DEPARTMENT OF EMBRYOLOGY 



191 



MORPHOLOGICAL STUDIES 



Growth and Development of the 
Chimpanzee 

In a comprehensive monograph Dr. A. H. 
Schultz has summed up the results of many 
years' study of the growth of the chimpanzee. 
The material used consists of several living 
animals studied during many years, of over 
100 preserved or fresh bodies from fetal to 
adult life, and 90 complete and incomplete 
skeletal specimens. The material has been 
obtained from many sources, in particular 
through the generous aid of the Yale Labora- 
tories of Primate Biology. 

In the chimpanzee, infancy lasts about 3 
years and adulthood is reached early in the 
nth year. During prenatal life the chim- 
panzee follows the curves of growth of man 
until about the end of the 7th lunar month, 
after which it gains in size much more slowly 
than the human fetus. At birth the chim- 
panzee is much smaller than man, averaging 
less than 1600 g. weight. The cranial capacity 
attains its full size at 6 years. This rapid 
growth of the brain and comparatively early 
cessation of growth are found in other pri- 
mates except man. The face grows much 
more rapidly than the brain part of the head, 
and in general the chimpanzee head, strik- 
ingly similar to the human in fetal life, be- 
comes more and more brutish as the animal 
grows older. The orbits move forward from 
a position underneath the brain until they are 
mostly in front of the brain. 

Skin pigmentation develops much earlier 
than in the colored races of man. The decidu- 
ous teeth erupt between the ages of 2.5 and 
14.5 months. The canine teeth are the last 
to erupt, a condition which occurs also in 
fossil man, although this sequence of erup- 
tion is much altered in recent man. The 
permanent teeth erupt, on the average, be- 
tween the ages of about 3 and 10 years. Here 
again the order of eruption resembles that of 
fossil man but not of modern man. 

Dr. Schultz gives full details of the meas- 
urements of the skeleton, the development 
of centers of ossification, and the times of 
closure of the epiphyses of the limb bones and 



of the fontanelles and sutures of the skull. He 
emphasizes the considerable variability which 
he has found. 

The Size of the Orbit and of the 
Eye in Primates 

Dr. A. H. Schultz has studied the relations 
between the body weight, the capacity of the 
orbit, and the size of the eye in 208 primates 
representing all major groups and widely dif- 
fering ages. Weight and orbital capacity 
alone have been studied in an additional 115 
specimens, and the capacity of the orbit only 
in still another series of great apes and man, 
totaling 187 more specimens. 

The absolute capacity of the orbit varies in 
recent, adult man between 16.5 and 31 cc, 
the average being approximately the same as 
the averages for chimpanzees and for orang- 
utans, but much smaller than the average for 
gorilla or for a few fossil men examined. 

All the large primates have proportionately 
much smaller orbits than do the small pri- 
mates. The relative capacity of the orbit is 
somewhat greater in females than in males 
and very much greater in young than in adult 
specimens. Among animals of the same 
species and age the largest individuals have 
proportionately the smallest orbits. From 
these varied findings it is evident that the 
relative capacity of the orbit is largely depend- 
ent upon body size regardless of genus, 
sex, or age. Only in some nocturnal primates 
have the orbits attained exceptional relative 
size. The relative capacity of the orbit in 
recent man is the second lowest among all 
primates, the minimum value occurring in 
female orang-utans. It seems, however, that 
this index was much higher in fossil man. 

The relative size of the eyeball varies in 
adult primates between 0.006 in male orang- 
utans and 2.243 in a female tarsier; that is, 
per unit of body weight the eye of the latter 
is 374 times larger than that of the former. 
The relative size of the eye of man stands 
very near the lowest value among adult pri- 
mates. Females have proportionately larger 
eyes than males. The relative size of the eye 



192 



CARNEGIE INSTITUTION OF WASHINGTON 



undergoes very profound changes during 
growth, becoming rapidly smaller in all the 
primates studied. 

The relative volume of the eye, even more 
than the relative capacity of the orbit, stands 
in a remarkably regular inverse ratio to body 
size, regardless of genus, sex, or age. The 
relative size of the eye diminishes rapidly 
with an increase in body weight up to about 
7 kg. Further increase in weight is accom- 
panied by a less intensive, but still consistent 
decrease in the proportionate volume of the 
eyeball. Only the nocturnal primates (except 
the potto) form an exception to this rule by 
having unusually large eyes in proportion to 
their body weight. 

The percentage relation between the vol- 
ume of the eye and the capacity of the orbit 
varies among adult primates between 17 in 
orang-utans and 179 in the tarsier. Man, with 
an index of 32, stands, in regard to this pro- 
portion, between the great apes and the 
majority of the Old World monkeys. This 
eye-orbit index is always larger in females 
than in males and very much larger in young 
than in adult specimens. Females, therefore, 
have larger eyes than males and infants much 
larger eyes than adults not only in relation 
to body weight, but also in proportion to the 
size of the orbits. In all fetuses and newborns 



studied the eyeball is so large in relation to 
its socket that it projects markedly beyond 
the orbital rim and therefore exophthalmos 
is normal in the fetus. 

Considering all the evidence, it appears that 
the size of the orbit is dependent upon the 
size of the eyeball in only the most general 
way and that the two structures can vary in 
size independently to a surprising extent. 

Anatomy of the Inguinal Region 

Basing his statements on his long experi- 
ence in comparative anatomy and in the 
medical dissecting room, Mr. A. Brazier 
Howell has summarized for the benefit of 
surgeons his views regarding the descriptive 
anatomy of the inguinal region. The paper, 
which cannot be summarized in brief com- 
pass, explains certain structures and peculi- 
arities of this region in man for which no 
ready explanation is given by embryology or 
comparative anatomy (for example, the linea 
semicircularis and the thin lower portion of 
the posterior rectus sheath, the accessory in- 
ternal oblique muscle, and even the inguinal 
ligament) as local variations in the arrange- 
ment and amount of connective tissue or 
muscle, arising from special stresses and 
strains, presumably phylogenetic as well as 
ontogenetic. 



NERVOUS SYSTEM 



Absorption from the Subarachnoid Space 

Messrs. R. O. Scholz and E. M. Ralston 
have re-examined the pathway of absorption 
from the subarachnoid space, using an im- 
provement upon the method introduced by 
Dr. Lewis H. Weed, by which one of the 
ingredients of the well-known Prussian blue 
reaction is introduced in solution into the 
subarachnoid space and then thrown down by 
addition of the other ingredients to render 
visible, by the presence of precipitated Prus- 
sian blue, whatever pathways the fluid may 
have taken. Because of the possibility that 
post-mortem diffusion may lead to false con- 
clusions, Scholz and Ralston prepared the 
brains of dogs and cats used in their experi- 
ments by a modification of the Altmann- 



Gersh method, freezing the tissues with 
liquid air and drying them in vacuo. The 
result showed that the nontoxic isotonic solu- 
tion of sodium ferrocyanide which they 
introduced into the cerebrospinal fluid passed 
into the venous system by way of the arach- 
noid villi and the arachnoid veins. Individual 
villi showed far greater concentration of 
Prussian blue than did individual veins. The 
result agrees in general with the conclusions 
Weed drew from his experiments of 1914. 

The Maturation of "Excitability" in the 
Precentral Gyrus of the Monkey 

It goes without saying that there is an 
embryology of function as well as of form. 
Much of the work of this Department and its 



DEPARTMENT OF EMBRYOLOGY 



193 



associates has been devoted to tracing the 
development of functional activities of animal 
tissues and organs. Volume 28 of the "Con- 
tributions to Embryology" contains an impor- 
tant monograph of Dr. Marion Hines and 
Dr. E. P. Boynton, reporting the results of 
seven years' study of the development of func- 
tion in the motor area (precentral gyrus of 
the brain) of the monkey. 

The authors' conclusions can best be under- 
stood by first recalling that in the adult brain 
cortex of mammals there is a special region 
along the anterior side of the Sylvian fissure, 
the precentral gyrus, which is associated with 
movements of the skeletal muscles and is 
generally considered to preside (in a way by 
no means fully understood) over the initiation 
of voluntary movements. When small areas 
in this region of the brain are stimulated, for 
example with an electric current applied 
through a fine needle, the result is contrac- 
tion of single muscles or small groups of 
muscles, causing discrete and well defined 
movements, such as extension of the leg, 
snarling movement of the lips, or flexion of 
the fingers. Dr. Hines calls such movements 
"idiokinetic." The cortical areas from which 
they may be elicited are arranged (as long 
ago described) in serial order in the precentral 
gyrus, the areas for the upper part of the body 
in the lower part of the gyrus and vice versa. 
When one side of the brain is stimulated, 
movements are elicited either on the opposite 
side of the body, or on the same side or both 
sides, according to the now well-known ana- 
tomical pattern of motor nerve tracts connect- 
ing the cortex to the spinal and medullary 
nuclei. - 

When Dr. Hines and Dr. Boynton stimu- 
lated the corresponding area in monkey 
fetuses from 66 to 125 days of gestation, the 
only movements elicited were of another type; 
they were less clearly defined, often involving 
fairly extensive muscle groups, and often 
representing or suggesting well-developed be- 
havioral complexes such as bodily progression. 
These movements lack the clear topographical 
representation of the idiokinetic movements. 
They are designated as "holokinetic." 

16 



The first idiokinetic movements were 
elicited at 135 days. In fetuses from 135 days 
to term (162 days), points from which idio- 
kinetic movements could be elicited were 
located in three distinct areas separated by 
areas containing insensitive ("silent") regions, 
holokinetic points, or "chalastic" points yield- 
ing muscular relaxation. After the first few 
weeks of extrauterine life a gradual encroach- 
ment of idiokinetic points upon the other 
areas occurred, the silent regions becoming 
reactive and holokinetic points giving place 
to idiokinetic points. This process of matura- 
tion continued until the adult type of topo- 
graphical projection emerged. After birth the 
movements elicited by stimulation of the pre- 
central gyrus at each stage of growth followed 
a definite pattern correlated with the type of 
posture, progression, and general behavior 
characteristic of the animal at the same stage. 
It is a noteworthy fact that certain complexly 
integrated muscular reactions ("use pat- 
terns") were elicited by electrical stimulation 
before the animal exhibited them spontane- 
ously. This hints that in the nervous system 
anatomical connection precedes functional 
use. 

The threshold of sensitivity to the electrical 
current became lower with age. The stability 
of a sensitive point, that is, the regularity with 
which a response can be obtained, increased 
with age. The stability of a point on the older 
cortices was demonstrated to be correlated 
with the frequency and intensity of the cur- 
rent used. The range of frequencies which 
elicited idiokinetic movements grew wider as 
the animals matured. 

This summary of an extensive work natu- 
rally cannot do full justice to it; there is not 
only a wealth of detail which must be read 
for thorough understanding, but also much 
theoretical discussion that will undoubtedly 
receive full and interested attention from 
other investigators of cerebral function. 

Defective Development of the 
Cerebral Cortex 

Those who study embryology cannot fail 
to be interested in abnormalities of the em- 



i 9 4 



CARNEGIE INSTITUTION OF WASHINGTON 



bryo. Teratology is one of the most ancient 
subdivisions of biology, and its problems, 
whether they arise through human sympathy 
in the tragic circumstances attending con- 
genital malformations, or through the imper- 
sonal hope of learning something more about 
normal development through the abnormal, 
have always fascinated the anatomists. The 
subject was a major interest of the founder 
of the Department of Embryology, Dr. Mall, 
and his two successors have each contributed 
personal investigations as well. A striking 
individual instance of malformation has been 
studied by Dr. P. A. M. F. Fitz-Gerald, of 
Dublin, while a guest worker in this Depart- 
ment. An infant of normal parents, born 
after normal pregnancy and an uncomplicated 
labor, failed to react to his surroundings after 
the fashion of normal babies, and did not dis- 
play normal motor activities. He died at 8 
months from an infection. At autopsy the only 
significant lesion was defective development 
of the cerebral cortex. The central area on both 
sides was smooth, owing to nondevelopment 
of the sulci; the central sulci were indicated 
only by shallow depressions, and the anterior 
opercula were undeveloped. The corpus cal- 
losum was well developed; the intermediate 
mass of the thalamus was absent. The brain 
stem and cerebellum were normal. There 
was no abnormality of the ventricular system. 
Dr. Fitz-Gerald points out that the defect 
represents essentially the retention of a fetal 
stage, yet development of the brain cannot be 
said to have ceased at any specific period. 
Rather, the chain of linked effects by which 
development of one region leads to growth 
in another, and thus to normal organization, 
must have been altered at a fairly early stage. 
Dr. Fitz-Gerald's careful analysis of the 
histology of the cortex in this case shows that 
the statement, frequently made in connection 
with cases of macrogyria, that the cortex is 
abnormally thick and the subcortical white 
matter deficient, is not correct. His interpre- 
tation is that the cerebral wall is imperfectly 
differentiated, retaining fetal characteristics, 
and that cortex and subcortical white matter 
are not fully distinguishable. 



Development of the Neuromuscular 
Spindle 

The ample supply of fresh human material 
available at the laboratory of the Department 
of Embryology has enabled Dr. Fidel Cua- 
junco, of the University of the Philippines, 
while a guest worker, to improve considerably 
our knowledge of the development of the 
neuromuscular spindles, the proprioceptive 
end organs of skeletal muscle. As early as 
n weeks of gestation he finds the first evi- 
dences of the impending development of 
spindles, namely, characteristic plexuses with 
dotlike granules, around myoblasts which do 
not as yet show any structural differences 
from the rest of the embryonic muscle cells. 
At 12 weeks a special grouping of nuclei 
about certain myoblasts indicates that these 
are to become the intrafusal fibers of spindles. 
The capsule appears at this time; the periaxial 
space is first seen at 14 weeks. By the 24th 
week the spindle has differentiated into fully 
adult character, except as to size. 

Pyramidal Lesion in the Monkey 

The nerve fibers which descend from the 
cerebral cortex to the spinal cord, constituting 
the pyramidal or corticospinal tract, are ob- 
viously of very great importance in the motor 
activities of the body. Numerous efforts have 
been made to study their function by cutting 
them and observing whatever alterations of 
movement and posture may occur. Dr. Sarah 
S. Tower, of the Johns Hopkins Anatomical 
Laboratory, has studied ten monkeys in which 
she was able to produce complete unilateral 
sections of the pyramidal tracts and one in 
which there was a complete bilateral lesion. 

In the animals with the unilateral lesion 
there occurred on the opposite side of the 
body, especially in the shoulder and hip 
regions, a weakness of muscular tone, of lesser 
degree than flaccid paralysis, described by Dr. 
Tower as hypotonic paresis. With this there 
is deficient initiation and execution of all 
performance by skeletal muscle, with elimina- 
tion of the nonstereotyped component move- 
ments and absence of all discrete use of the 
digits. The reflexes are sluggish and weak. 



DEPARTMENT OF EMBRYOLOGY 



195 



As a result, there is diminished general use 
of the affected extremities. Initiative in move- 
ment is delegated to the normal side, but if 
the normal side is restrained the affected side 
can, with sufficiently strong excitation, be 
brought to act. Owing to the elimination of 
nonstereotyped components involving discrete 
use of the digits, corrective movements for 
unusual postures, and the ability to take 
accurate aim or to modify movement in the 
course of execution, the activity of the paretic 
side is reduced to a limited number of stereo- 
typed performances, employed only when 
they are indispensable. Those most in use are 
maintenance of posture, including righting, 
orientation of the body as a whole, progres- 
sion, reaching-grasping, scratching, striking, 
and kicking. 

In the one animal which survived bilateral 
lesion, the effects on muscular tone, reflexes, 
and use were similar although they involved 
the axial musculature as well as that of the 
extremities. Whereas, however, the monkey 
with a unilateral lesion compensates by in- 
creased use of the normal side, employing the 
paretic side only in symmetrically patterned 
activities and in support, the monkey with the 
bilateral lesion was compelled to rely upon his 
cortical extrapyramidal motor mechanism. 
He therefore worked out by trial and error, 
as far as he could, a series of stereotyped per- 
formances, by which he was able to sit, stand, 
progress, and take food. The highly interest- 
ing details must be read in the original paper 
in order to appreciate them. 

From these observations, Dr. Tower pic- 
tures the pyramidal tract as exerting, in the 
first place, a tonic activity, which contributes 
to the excitatory state in the spinal cord, sup- 
porting muscular tone, facilitating, reinforc- 
ing, steadying, and moderating whatever 
tonic or phasic activity may be set in action 
at segmental or suprasegmental levels. In 
the second place, the pyramidal tract initiates 
movement or speeds initiation, entering into 
all complex somatic motor activity to confer 
upon the stereotyped extrapyramidal per- 
formances all those modifications of pattern 
and adjustments in execution which make for 
aim, accuracy, economy, lability, and finish. 



Although a considerable capacity for volun- 
tary movement survives pyramidal section, 
especially if the lesion is bilateral, yet for the 
more labile, more discriminating, and more 
minutely controlled corticospinal activities the 
pyramidal tract is the outstanding voluntary 
motor pathway. 

Nonexistence of Emergent Fibers in the 
Dorsal Roots of the Spinal Nerves 

Whether or not the dorsal or posterior roots 
of the spinal nerves, which carry afferent 
(sensory) fibers into the spinal cord, also con- 
tain emergent fibers is an old question, which 
has been answered in the affirmative by some, 
in the negative by others. Dr. W. H. L. 
Westbrook and Dr. Sarah S. Tower have re- 
investigated the problem, using a new method 
or sequence of experimental steps. In adult 
cats three dorsal root ganglia were removed 
under anesthesia, and time (4 weeks) was 
allowed for degeneration of all the nerve 
fibers proceeding from the ablated ganglia. 
Next, the proximal stumps were severed close 
to the cord and the dorsal roots, now isolated 
from the rest of the nervous system, were 
left in place for 2 weeks. If there had been 
originally any emergent fibers from the cord, 
these would have escaped degeneration after 
removal of the ganglia. They would, how- 
ever, have degenerated after the proximal sec- 
tion and, in view of the time elapsing before 
autopsy, they would (if myelinated) have 
been in process of degeneration and would 
have been visible in the Marchi preparations. 
No such fibers were observed. 

By use of the Bielschowsky technique 
much evidence was obtained that after abla- 
tion of the ganglia or section of the roots, 
there is prompt and vigorous growth of 
extraneous fibers into the vacated root. This 
finding no doubt explains the supposed 
emergent fibers seen by some previous 
workers. Careful search of the Bielschowsky 
preparations revealed during the critical 2 
weeks after ganglionectomy no fibers which 
were not unmistakably either degenerating or 
regenerating. It is concluded that the concept 
that nerve fibers emerge from the spinal cord 



196 



CARNEGIE INSTITUTION OF WASHINGTON 



into the posterior roots in adult mammals is 
without foundation. 

Fibrillation in Denervated Muscle 

It has usually been thought that the atrophy 
of skeletal muscle which occurs after its nerve 
supply is cut is due to disuse. A contrary 
hypothesis suggests, however, that denervated 
skeletal muscle atrophies because it is fatigued 
by ceaseless fibrillary contractions. Dr. Sarah 
S. Tower has found by experimental observa- 
tion that fibrillation caused by denervation 



continues for months and even for more than 
a year, indeed as long as the denervated tissue 
is recognizable as muscle. The persistence of 
fibrillation is therefore such as to permit the 
hypothesis that it underlies the atrophy of 
denervated muscle. 

Atrophy also follows severance of the tendi- 
nous attachments of muscle. Dr. Tower 
finds, however, no fibrillation in tenotomized 
muscle. She suggests that even in this case, 
spasmodic contraction going on to myostatic 
contracture may produce atrophy by exhaust- 
ing the muscle. 



THE CHROMOSOMES 



Chromosome Rearrangement and 
Evolution 

Dr. C. W. Metz, in a lecture given at the 
International Congress of Genetics at Edin- 
burgh in September 1939 (but not yet pub- 
lished because of the interruption of the Con- 
gress by the outbreak of war), reviewed his 
recent work on chromosome rearrangement 
in the dipteran fly Sciara. The enormous size 
of the salivary-gland chromosomes in Diptera 
makes it possible to observe directly any 
changes which may occur in the chromo- 
somes, whether spontaneous or induced, as 
indicated by the pattern of chromatic discs. 
Dr. Metz and his co-workers have found that 
in Sciara small localized alterations of pattern, 
such as deficiencies and duplications involv- 
ing one to four discs, are very common, 
whereas translocations or inversions of large 
portions of chromosomes, which are frequent 
in Drosophila, are rare in Sciara. The same 
is true of hybrids between species of Sciara, 
bred in the laboratory. 

Spontaneous inversions and translocations 
of parts of chromosomes have been called 
upon to explain the evolutionary differentia- 
tion of species; yet there are indications that 
the genus Sciara, in which large changes are 
rare, is at the present time undergoing 
marked evolutionary change. Dr. Metz sup- 
poses therefore that the small modifications 
of chromosomes characteristic of Sciara must 
also provide an adequate mechanism of evo- 
lutionary change in the germ plasm. 



Experimental alteration of chromosomes, 
by irradiation of the male flies, is considerably 
less effective in Sciara than in Drosophila. 
Dr. Metz offers the conjecture that such dif- 
ferences in susceptibility to X-rays may de- 
pend upon some sort of protective sheath 
about the chromosome threads, which is more 
easily modified by the rays in one species than 
in another. If, for example, in Sciara the 
chromosome sheath is more resistant than in 
Drosophila, we might expect chromosome 
alterations to be restricted to minute localized 
changes such as could occur within the sheath. 

The Mechanism of Induced Chromosome 
Rearrangement 

As previously reported, Metz and Boche 
found that in oocytes of adult females of 
Sciara the chromosomes are very resistant to 
irradiation, as judged by the difficulty of 
inducing chromosome rearrangements. In 
sperm cells rearrangements were readily ob- 
tained. Since this result is quite different 
from that of similar work with Drosophila, 
it was thought that possibly the difference 
was due to difference in the mode of develop- 
ment of the oocytes in the two genera. In 
Sciara the adult females contain only rela- 
tively old oocytes, and these might be espe- 
cially resistant to irradiation because their 
chromosomes are in a condensed state. 

An extension of the study by Dr. Metz and 
Dr. Bozeman, however, leads to a different 
interpretation. The results indicate that in 



DEPARTMENT OF EMBRYOLOGY 



197 



Sciara the chromosomes are resistant to irradi- 
ation for a much longer period than was 
formerly supposed, even during the prophase, 
when they are long and threadlike. In other 
species the chromosomes in such a state are 
sensitive to irradiation. The only plausible 
explanation of the relative insensitivity of 
Sciara chromosomes seems to be that the 
broken ends of irradiated chromosomes fail 
to move enough to form new combinations. 
On cytological examination of irradiated eggs, 
Dr. Metz and Dr. Bozeman find no evidence 
of clumping or breakage of chromosomes, a 
fact which supports the hypothesis that the 
infrequency of rearrangements within chro- 
mosomes after irradiation is due to lack of 
chromosome movement. 

Organization of the Giant Chromosomes 

In spite of their relatively great size, the 
giant salivary-gland chromosomes are still 
absolutely small enough to test the highest 
powers of the microscope, and several dif- 
ferent interpretations of their structure have 
been put forward. Dr. Metz, in an article 
in the American Naturalist, gives reasons, 
backed by photographs, for thinking that the 
chromosomes consist of a series of transverse 
chromatic discs, seen in side view as cross- 
bands, and that each pair of discs is separated 
by a single layer of nonstaining (achromatic) 
droplets embedded in the true chromosome 
substance, which extends longitudinally be- 
tween the droplets from one disc to the next. 
Dr. Metz supplies diagrams explaining how 
other students of the subject may have arrived 
at erroneous interpretations by analyzing the 
same appearances in other ways. 

Spontaneous Chromosome Breakage 

In a preliminary communication Dr. Metz 
reports that in Sciara reynoldsi one chromo- 
some pair regularly breaks into two segments 
during development, in the salivary glands 
but not in ordinary embryonic cells. This 



provides additional evidence that the salivary- 
gland chromosomes are highly modified struc- 
tures. Here, as in the somewhat similar case 
described previously in S. ocellaris, the break 
probably occurs at the region of the centro- 
mere. It is postulated that two centromeres 
are present and that they separate to effect 
the break. The phenomenon may have a 
bearing on the mechanism of evolutionary 
change in chromosome number. 

An Evolutionary Change in Chromo- 
some Shape 

In the fly Sciara ocellaris two types of 
chromosomal pattern are found. In the 
"bisexual" strains (in which single females 
give both male and female offspring) there 
are 4 V-shaped chromosomes and 4 rods. In 
the "unisexual" strains (in which a single 
female gives only male or female off- 
spring) there are 2 V's and 6 rods. In the 
closely related species S. reynoldsi there are 
always 4 V's and 4 rods; all the known strains 
are "bisexual." In both species the two pairs 
of V's are autosomes, the sex-chromosome 
pair being rod-shaped. 

By crossing the "bisexual" and "unisexual" 
strains of S. ocellaris, Dr. Helen V. Crouse ob- 
tained an F x generation showing 3 V-shaped 
chromosomes and 5 rods. The odd V and 
one of the rods appear to be of the same 
length, and it was supposed that the V chro- 
mosome had originated from a rod by the 
occurrence of a large transposition. The large 
chromosomes of the salivary glands, however, 
show no such transposition, and Dr. Crouse 
now supposes that this change in the form 
of the chromosome was produced by trans- 
location of the point of attachment of the 
spindle fiber. The genetic significance of the 
heteromorphic chromosome pair and its rela- 
tion to the determination of "bisexuality" and 
"unisexuality" in S. ocellaris remain to be 
investigated. 



198 



CARNEGIE INSTITUTION OF WASHINGTON 



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Gemmill, C. L., G. O. Gey, and R. Austrian. 
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G. E. Seegar, and M. K. Gey. The 

cytological and cultural characteristics and 
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Gey, M. K. See Gey, G. O. 

Grollman, A. See Flexner, L. B.; Gersh, I. 

Hartman, C. G. Studies on reproduction in the 
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See Marker, R. E. 



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Heuser, C. H. The chimpanzee ovum in the 
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tions of the mechanism of induced chromo- 
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Roberts, R. B. See Flexner, L. B. 

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Wintrobe, M. M. See Rich, A. R. 



DEPARTMENT OF GENETICS 



Cold Spring Harbor, Long Island, New Yor\ 
A. F. BLAKESLEE, Director 



The Department of Genetics is interested 
not alone in the detailed mechanisms of 
heredity — how chromosomes with the genes 
which they carry are distributed at the divi- 
sion of cells in reproduction and growth, and 
how chromosomes and genes are changed 
under various types of stimulation. It is inter- 
ested in the broader problems of evolution, 
and attempts to relate its laboratory findings 
to the processes which have brought about the 
diversity in nature as we see it today. It is 
specifically interested in growth and develop- 
ment and the directive forces inherent in the 
assemblage of genes possessed by the living 
plant and animal. It is interested in the 
action of hormones, which in many forms 
are the medium through which control of 
development is exercised. It is equally inter- 
ested in cases in which the mechanisms for 
orderly development break down and uncon- 
trolled growth results. Through these dif- 
ferent interests and different points of view 
a clearer picture is unfolding of how the 
living organism becomes what it is. 

Detailed reports of the work of the dif- 
ferent research groups for the past year, end- 
ing September i, are given in the following 
pages. The chief results of these investiga- 
tions may be briefly summarized. 

The group which has been concerned pri- 
marily with the gene has contributed further 
evidence on the nature of genes by means of 
induced mutations. Drs. Demerec and Sutton 
have found evidence which indicates that 
there is a sensitive region on each side of a 
gene. If the chromosome is broken within 
this sensitive region and the broken segment 
attached to some unrelated section, the gene 
is frequently affected. The length of the 
sensitive region varies with the locus and is 
also influenced by the nature of the recipient 
section. Dr. Kaufmann's studies indicate that 
broken chromosome segments induced by 
X-rays in the sperm of Drosophila do not 



rejoin for at least 16 days after the treatment, 
probably not until the sperm enters the egg. 
Drs. Demerec and Hollaender found that 
monochromatic radiation of 2280, 2650, and 
2950 A produces lethal mutations in the sperm 
of Drosophila. Drs. Demerec, Kaufmann, 
and Sutton, in collaboration with Dr. Tuve, 
of the Department of Terrestrial Magnetism, 
have found that changes in chromosomes of 
Drosophila induced by neutrons are similar 
to changes induced by X-rays. 

The group which has been interested 
especially in the grosser structure of chromo- 
somes has continued to explore the numerous 
problems in development and heredity which 
the new method of inducing chromosome 
doubling has opened up. By means of in- 
duced periclinal chimeras with different 
chromosome numbers, Miss Satina has defi- 
nitely established the presence of three germ 
layers in Datura and determined the contri- 
bution which these layers make to the dif- 
ferent plant organs. Dr. Sinnott has analyzed 
the influence of chromosome number upon 
the number, size, and shape of cells and also 
upon the relative frequencies of division in 
different planes which are responsible for 
differences in size and shape of fruits in 
cucurbits. Drs. van Overbeek and Conklin 
have studied the effect of various stimuli on 
the reproductive processes in plants and con- 
clude that there are different steps in the pro- 
duction of fertile seed which require dif- 
ferent stimuli for their initiation. Auxin is 
necessary for retaining the ovaries. The 
stimulus for later development of egg cells, 
which, if discovered, might be used to induce 
parthenogenesis, is believed to be proteina- 
ceous in nature. Cooperative studies with Dr. 
W. I. Robbins on the physiological differences 
between \n, in, yi, and 4/z Daturas have 
been started and sterile cultures of excised 
roots of these chromosomal types have been 
secured for experimentation. By means of 



202 



CARNEGIE INSTITUTION OF WASHINGTON 



induced tetraploids in the dioecious plant 
Melandrium dioicum, Dr. Warmke has 
shown that the X chromosome carries factors 
for femaleness, the Y carries even stronger 
factors for maleness, and the autosomes have 
no significance in sex expression. By chang- 
ing the balance between the numbers of X 
and Y chromosomes, hermaphrodites have 
been secured, and a method has been devised 
for purifying this dioecious species through 
selfing such hermaphrodites. By finding chro- 
mosomal bridges, Dr. Bergner has evidence 
that inversions are not infrequent in races 
of Datura. She has evidence of position effect 
from results of a spontaneous somatic inter- 
change. Miss Satina is now able to identify 
all the chromosomes in Datura as well as to 
distinguish their individual ends by study of 
structural differences. Mr. Avery has sum- 
marized the known genes in Datura. Seventy- 
two have been located in particular chromo- 
somes. Over 380 genie types have been recog- 
nized the genes for which have not yet been 
located. 

The group working on genetic aspects of 
development in mice have completed the 
experimental part of an extensive study upon 
the mechanism responsible for the inheritance 
of the tendency to produce spontaneous leu- 
kemia. The results of previous hybridization 
studies, which include only the first hybrid 
generation and a first backcross, could be 
interpreted equally well by the action of genes 
or of nonsegregating materials. The reduced 
incidence of leukemia in the backcross did 
not indicate whether the segregation of genes 
was giving these animals diverse leukemic 
potencies or whether each mouse "inherited" 
the same dilute leukemic potency, which was 
expressed less frequently because weaker. 
The only possible approach to such a question 
was to make a breeding test of each backcross 
animal. This experiment has now been re- 
peated, with the addition of breeding tests 
of 50 backcross animals, from each of which 
over 50 young have been bred, making a total 
of over 2800 offspring in a second backcross 
generation that have been raised, held until 
death, and autopsied. The conclusions are 
given in terms of the incidence of leukemia 



in each of the second backcross families: in- 
stead of classifying the backcross animals into 
two groups, leukemic and nonleukemic, each 
backcross animal is classified according to the 
performance of its offspring. This appears to 
be the first time that such an analysis of a 
segregating generation has been attempted in 
the genetic study of any spontaneously occur- 
ring malignant growth. Although the histo- 
logical diagnoses are incomplete, a prelimi- 
nary survey of the data indicates with cer- 
tainty that an interpretation calling for one 
outstanding gene pair is eliminated. 

The group interested in endocrine glands 
has concentrated its work on the action of 
the hormones of the pituitary. Through use 
of large numbers of pigeons whose pituitary 
glands had been removed, two pituitary hor- 
mones — prolactin and thyrotropin — have been 
shown to have special action on the growth 
and maintenance of the pancreas in these 
animals. Though these and all other pitui- 
tary hormones are unable to exert this action 
in completely fasting birds, either prolactin 
or thyrotropin is partly effective and a com- 
bination of these two hormones produces 
abnormally large pancreases in normal birds 
and in those whose pituitaries have previ- 
ously been removed. These hormones exer- 
cise this action partly by increasing appetite 
and food consumption, but force-feeding 
alone without hormone injection only par- 
tially sustains the pancreas. It is not yet 
known whether or to what extent these hor- 
mones have a similar action on the pancreas 
of other animals and man. Still another ac- 
tion of prolactin is found to be much in- 
creased or potentiated by some other product 
or products of the pituitary gland. When 
purified prolactin is injected into pituitaryless 
pigeons for as much as 10 days it increases 
the weight of their crop sacs much less than 
when the same amount of prolactin is ad- 
ministered in impure (unseparated) form 
(Drs. Schooley, Riddle, and Bates). These 
instances extend the known range of processes 
regulated by the pituitary gland and provide 
further instances of interrelationship and 
synergism among the pituitary hormones. A 
useful method was developed for assaying 



DEPARTMENT OF GENETICS 



203 



pituitary extracts and preparations for their 
ability (adrenotropin) to stimulate the adrenal 
glands. Two-day-old chicks are injected daily 
for 5 days and any enlargement of their 
adrenals is then determined by weighing. 
Several other pituitary and nonpituitary sub- 
stances have been shown to have no effect 
upon this reaction on cortical tissue in the 
chick, and the method has the additional ad- 
vantage of permitting a simultaneous assay 
of thyrotropin and gonadotropin in the prepa- 
rations thus examined. Largely in conse- 
quence of advantages possessed by this 
method of assay, it has also been possible to 
devise a method of preparing highly potent 
adrenotropic fractions essentially free from 
prolactin, thyrotropin, and gonadotropin (the 
relationship of LH, or luteinizing hormone, 
to adrenotropin is uncertain) (Drs. Bates, 
Riddle, and Miller). An unusual result was 
obtained from a combination of two agencies 
which separately reduce the metabolic rate. 
It is well known that both fasting and 
hypophysectomy cause a very marked de- 
crease in rate of heat production in various 
animals, including pigeons. It is now estab- 
lished that when immature (2-month) pi- 
geons are fasted for 10 days following removal 
of their anterior pituitary glands, the decrease 
in their rate of heat production, measured at 
either 25 ° or 30 C, is less than that in their 
unoperated mates. This result may therefore 
be described approximately by the expression 
"one plus one equals one-half" (Dr. Riddle 
and Mrs. Smith). 

Dr. Steggerda, who heads a group on 
anthropology, has spent a large part of the 



past year on his manuscript on studies in 
Yucatan, but has also carried on field work 
on racial differences. He finds that the 
growth pattern for Zuni children is practically 
the same as that previously demonstrated for 
Navajo, Maya, Negro, and Dutch white chil- 
dren. All these children grow rapidly at 
about 6 years of age, then decrease in their 
rate of growth until 9 or 10 years, and then 
have another spurt of growth which lasts 
until about 14 years, when the rate of growth 
begins to fall off rapidly. The order in which 
the permanent teeth appear in the mouth is 
the same for all the races considered. In 
general the lower teeth erupt earlier than the 
upper ones. Tooth eruption is somewhat 
earlier in females than in males. Dr. Steg- 
gerda has discovered an instrument in use for 
getting sections of wool fibers with which he 
has been able to cut 150 cross sections of 
individual human hairs at one time, instead 
of only one, as was the case with the usual 
microtome method. It has thus become pos- 
sible to analyze statistically hair size and 
shape, which Steggerda finds vary greatly in 
the same individual. He has found statisti- 
cally significant differences among the Ameri- 
can Indians, Negroes, and Dutch whites in 
respect to hair characters. Steggerda has 
tested the value of different anthropometric 
measurements as criteria for distinguishing 
identical twins, which are the products of a 
single egg, from fraternal twins, which come 
from two different eggs. Vertex height, 
weight, and certain other measurements were 
found to be statistically more reliable than 
many that have been used. 



CHROMOSOME INVESTIGATIONS 

A. F. Blakeslee, A. G. Avery, A. D. Bergner, S. Satina, H. E. Warm\e, J. T. Buchholz, 
M. E. Con\lin, E. W . Sinnott, and f. van Overbee\ 



In our last two annual reports we have 
described methods of inducing the doubling 
of chromosome number by use of the alkaloid 
colchicine and have given preliminary results 
of studies on the effects of induced polyploidy. 
Colchicine is not the only chemical which will 
induce doubling of chromosome number, al- 



though it appears to be the best so far known 
for this purpose. Phenyl urethane, first used 
by Lefevre to induce polyploidy, we have 
found to be potent, but effective with Datura 
only within a narrow range of concentrations. 
Thus, when seeds were soaked in a saturated 
solution (about 0.01 per cent) for 2 days, 



204 



CARNEGIE INSTITUTION OF WASHINGTON 



75 per cent of. those which lived appeared to 
be tetraploid. However, seeds soaked in 0.009 
per cent solution for 4 days gave no 
tetraploids. 

Periclinal Chimeras 

New tools often make possible new insights 
into life processes. The method of doubling 
chromosome number at will is proving to be 
a tool of greater value than was at first real- 
ized in throwing light on problems of devel- 
opment and evolution. A striking example is 
the formation of periclinal chimeras, which 
frequently result from colchicine treatment 
when only some of the germ layers are af- 
fected by the drug. Further studies made by 
Miss Satina of 68 periclinal chimeras have 
definitely demonstrated the presence of three 
independent germ layers in the primordia of 
Datura. The cells of the central core, which 
have been generally believed to constitute a 
tissue of independent origin, she has shown 
to be derived entirely from the third germ 
layer. Various combinations of in, 4/z, and 
8« layers have given nine types of periclinal 
chimera in which one, two, or three germ 
layers were polyploid. The most frequent 
changes in chromosome number occurred in 
the outermost germ layer, the least frequent 
in the second layer. At very early stages of 
development the three germ layers differ in 
the contribution which they make to the pri- 
mordia of different organs. Thus, most of 
the inner tissue of leaves, petals, and sepals 
is formed by the second layer, while the inner 
cells of the stamens and of the pistil consist 
chiefly of cells which have originated from 
the third or innermost layer. The theory 
current in textbooks is that pistils and stamens 
are phylogenetically closely related to leaves. 
If the ontogenetic development in the dif- 
ferent organs can be properly used as an 
index to phylogenetic relationships, our find- 
ings seem to indicate that sepals and petals 
are closely related to leaves but that the rela- 
tion of pistils and stamens to leaves is more 
remote. 

The loose inner tissue of the style through 
which the pollen tubes grow appears to be 
formed chiefly, if not entirely, from the outer- 



most or first germ layer, which gives rise to 
epidermis of stems and leaves. The periclinal 
chimeras appear to show that it is this loose 
inner tissue of a in style which causes the 
in pollen tubes from a \n plant to burst 
before reaching the ovary, since the style of 
a periclinal chimera with a in epidermis but 
otherwise \n causes in pollen tubes to burst 
in the same way as does a style of a plant 
which is in throughout. 

This past season more than 100 plants from 
colchicine-treated seeds were recorded for 
polyploidy from appearance and tested for 
periclinal chimeras by histological study. If 
only a single germ layer had its chromosomes 
doubled, the greatest visible effect was pro- 
duced when the innermost layer was tetra- 
ploid, and the least effect when the epidermis 
was tetraploid. Thus the ability to produce 
periclinal chimeras through the use of colchi- 
cine has enabled us to label the different germ 
layers and to determine the contribution 
which each makes to the development of the 
various organs of the plant. 

Polyploidy in Cucurbits 

One of our profitable cooperative investiga- 
tions is the study of the effects of polyploidy 
upon the developmental processes in cucurbits 
which is being carried on by Dr. Sinnott with 
the assistance of Mrs. Alicelia Franklin. 

The investigations on the relation of chro- 
mosome number to fruit size and shape in cu- 
curbits have been considerably extended, and 
data are now available on twelve pure lines 
in the genera Cucurbita and Lagenaria. In 
every case there is observable the tendency for 
the tetraploid race to have wider and shorter 
fruits than the diploid race from which it 
was derived. This is evident not only in the 
fruits, but also in the leaves. The dimension 
at right angles to the longitudinal axis of the 
organ is increased much more than the others, 
evidently by more extensive cell division in 
this direction. The final size of the organ is 
approximately the same in tetraploids as in 
diploids, no sign of gigantism being seen 
except in one line. Since the cells are twice 
as large in tetraploids as in diploids, this 



DEPARTMENT OF GENETICS 



205 



means that the former have only about half 
as many cells per organ. Evidently increasing 
the chromosome number decreases the num- 
ber of cell divisions, although it increases the 
size of the cells. 

Developmental studies on fruits of these 
various lines have been continued and con- 
siderably extended. The lines all agree in 
showing that the tetraploids are larger-celled 
from the beginning and that this advantage 
is maintained until the end of development. 
The problem of the relation between the 
cellular differences and the differences in 
fruit shape between tetraploids and diploids 
is being examined. 

Attempts to Induce Parthenogenesis 

The success of efforts to find a method of 
inducing an increase in the number of chro- 
mosomes has led to search for methods by 
which to reverse the process. The counter- 
part of the colchicine method, by which the 
chromosomes in the cells of plants are 
doubled in number, would be a method 
which would reduce the number of chromo- 
somes by half. If this could be done experi- 
mentally it would be of considerable practical 
and theoretical significance. By the combina- 
tion of such a method with colchicine treat- 
ment, a quick way would be made available 
to establish pure lines of plants. The method 
used by itself would enable one to obtain 
simpler forms from naturally occurring 
multiple diploids, which would mean that 
the wheels of evolution could be turned back. 
With this in mind, it was deemed profitable 
to study the problem of induced partheno- 
genesis^ which appears the most logical 
method to obtain plants with reduced chromo- 
some number. With numerous growth hor- 
mones available, either in crystalline form or 
as highly concentrated extracts, it seemed 
worth while to test their possible utility for 
the induction of parthenogenesis. The prob- 
lem has been studied during the summer of 
1940 by Drs. van Overbeek and Conklin. 

Some form of auxin was found to be 
indispensable for retaining the developing 
ovaries on the plants, and, of the different 



kinds tested, napthalene acetic acid proved 
to be the best. Not only does auxin induce 
development of the carpels, as was earlier 
found by Gustafson and reported by us last 
year for Datura, but if injected into the 
ovaries it also caused a considerable enlarge- 
ment of the ovules. When applied as an 
emulsion on the outside of the ovary or just 
below the flower on the peduncle, it caused 
development of the carpels alone, with hardly 
any development of the placenta and ovules. 

In addition to the growth of the carpels 
and enlargement of the ovules, a pseudo- 
embryo in 4« Datura was formed under the 
influence of napthalene acetic acid. This 
pseudo-embryo, which is a novel discovery, 
appears to be formed by proliferation of the 
inner layer of the integument, sometimes 
called the endothelium. It consists of several 
hundred compact cells rich in protoplasm. In 
an early stage of development it fills the space 
normally taken by the embryo sac. The 
pseudo-embryo is surrounded by cells which 
degenerate, perhaps under the influence of the 
developing pseudo-embryo. About 14 days 
after treatment the pseudo-embryo, like the 
normal embryo, is found lying in the em- 
bryo sac, surrounded by degenerating in- 
tegumental cells. The chief difference in ap- 
pearance lies in the fact that the normal 
embryo sac is filled with endosperm tissue, 
whereas the embryo sac of the treated plant 
does not contain anything but the pseudo- 
embryo. 

Attempts to stimulate ovules beyond the 
stage induced by auxin through additional 
injections of traumatic acid, biotin, panto- 
thenic acid, many vitamins and other physi- 
ologically active substances, yeast, and pollen 
extracts have failed so far. 

A study of the literature in combination 
with our own experiments indicates that at 
least two different substances are involved 
in the production of parthenogenetic embryos, 
each one initiating a definite step in the de- 
velopment of the embryo and the seed and 
fruit in which it is contained. One of the 
substances responsible for the first step is 
either auxin or a substance leading to its 
release in the ovary. This step is completely 



206 



CARNEGIE INSTITUTION OF WASHINGTON 



under experimental control. Indications are 
that the other substance has a limited area of 
activity and may be proteinaceous in nature. 
If this substance could be identified or ex- 
tracted and introduced into the embryo sac, 
the problem of artificial parthenogenesis 
might be solved. Though we have not yet 
solved this problem, we have learned some- 
thing about the stimuli required for the 
various processes involved in setting of fruits 
and in the development of seeds. 

Polyploidy in Excised Roots 

Since doubling of chromosome number is 
an established method of evolution of plants 
in nature, it seems desirable to learn what we 
can of the physiological as well as the morpho- 
logical responses to increased amounts of 
chromosomal material. We are fortunate in 
having secured the cooperation of Dr. W. I. 
Robbins in an attack upon the physiological 
phases of the problem through the use of 
excised roots of m, in, ?,n, and \n Daturas. 
These can be grown in sterile cultures on 
synthetic nutrient media under more closely 
comparable conditions than would be pos- 
sible when dealing with entire plants. Some 
difficulty was at first encountered in getting 
sterile roots from cuttings of these four 
balanced chromosomal types. Now that this 
problem appears in the way of being solved, 
it should soon be possible to determine what 
differences exist among these types in physi- 
ological reactions. Dr. Robbins reports that 
he has induced an excised root of a 2« 
Datura to grow 5 cm. in less than 24 hours. 
This is probably the record so far for speed 
of growth of an excised root. 

Polyploidy and the Sex Mechanism in 
Melandrium 

Most flowering plants are hermaphroditic, 
having both pistils and stamens. A few, such 
as the poplars and willows, are dioecious 
and, like the higher animals, have the sexes 
separate. There is evidence that doubling of 
chromosome number has been of evolutionary 
significance among dioecious as well as among 
the more common hermaphroditic species of 



plants. The dioecious species Melandrium 
dioicum is insect- rather than wind-pollinated, 
has sex chromosomes which can be readily 
distinguished, and in other ways is especially 
adapted to genetic study. For these reasons 
it has been chosen for an intensive study 
which has been carried on by Dr. Warmke. 
It is now possible to add considerable to our 
preliminary report of last year. 

The role of the X chromosome and auto- 
somes in sex determination in Melandrium 
is now definitely established. The X is female- 
determining, as shown by the following 
series: 



Chromosome 
constitution X/Y ratio 

4A + XY 1.0 

4A + XXY 2.0 



4A + XXXY 

4A + XXXXY 



Sex 

Male 

Male 
(rare <? blossom) 

3.0 Male 

(occasional § blossom) 

4.0 Hermaphroditic 

(occasional c? blossom) 



The autosomes in Melandrium are unim- 
portant in sex determination. In the follow- 
ing series the ratio of X chromosomes to 
autosomes is changed by a factor of 3, but 
sex is not altered. 

Chromosome 

constitution X/A ratio Sex 

2A + XXX 1.5 Female 

4A + XXXXX 1.25 Female 

2A + XX I 

3A4-XXX > 1.0 Female 

4A+XXXXJ 

4A + XXX 0.75 Female 

3A + XX 0.66 Female 

4A + XX 0.5 Female 

Thus sex is determined in Melandrium by 
a balance between X and Y chromosomes, and 
not between X chromosomes and sets of auto- 
somes, as in Drosophila. 

It is evident that hermaphroditic plants 
are at an advantage over dioecious animals 
and plants in that they can be quickly 
rendered homozygous through selfing for a 
few generations. In an attempt to free our 
dioecious Melandrium material from possible 



DEPARTMENT OF GENETICS 



207 



heterozygosity, a relatively rapid method of 
purifying the stocks through selfing was de- 
vised. By adding an extra chromosome to 
diploid plants, individuals with the constitu- 
tion 2A + XXY have been obtained. These 
plants are predominantly male, but produce 
a few self-fertile hermaphroditic blossoms. 
Among the offspring of such flowers are 
normal in males and females and more plants 
of the type 2A + XXY. These latter may 
again be selfed, and the process continued as 
long as segregation occurs. When the stock 
is sufficiently pure, the extra chromosome 
may be eliminated, leaving a relatively homo- 
zygous stock, consisting of normal 2A + XY 
males and 2A + XX females. The long and 
laborious task of purifying a dioecious stock 
through brother-and-sister matings is thus 
avoided. 

A sexually reproducing race deficient for 
two sex chromosomes has been produced in 
Melandrium. By selecting and intercrossing 
47/ plants which had lost one sex chromo- 
some through non-disjunction, plants defi- 
cient for two sex chromosomes have been 
obtained. Such plants, 4A + XX (female) and 
4A + XY (male), are tetraploid for autosomes 
but diploid for sex chromosomes. These 
plants are viable and fertile; it was expected 
that by crossing them, a true-breeding race 
consisting of approximately equal numbers of 
males and females similar to the parents 
would be obtained. Incomplete field records 
bear out this expectation but reveal a con- 
siderable excess of male plants. It is possible 
these findings may offer an explanation for 
the polyploid species in willows, for example, 
in which the autosomes appear to be doubled 
but in which only a single pair of sex chromo- 
somes is evident. 

Chromosome Inversions 

A major problem of our group has had to 
do with the chromosomal changes which 
occur in nature. Earlier reports on segmental 
interchange in Datura stramonium have been 
based on study of 680 races. It is now possible 
to report on a preliminary survey by Dr. 
Bergner of hybrids between our standard 



Line 1 of this species and 36 other races in 
respect to evidence for inverted segments in 
the chromosomes. When crossing over takes 
place in a plant heterozygous for an inverted 
segment distal to the centromere, a chromatid 
bridge and a fragment may result. Chro- 
matid bridges were found occasionally in most 
of these intra se hybrids, those found at T I, 
M II, A II, and T II being considered as 
reliable evidence of inversions, but their fre- 
quency probably would not be above 2 per 
cent as a maximum. The bridge usually was 
heavy, but not always. The fragment could 
be found only very rarely, and when it was 
seen it usually was quite small and lay close 
to the bridge. These observations led to the 
conclusion that inversions which do not in- 
clude the centromere are present in many 
races of Datura stramonium but that they 
are short regions and lie close to the ends of 
the chromosomes. 

In three species hybrids, at least two dif- 
ferent chromosomes gave evidence of inver- 
sions. Other than the relatively greater fre- 
quency of chromatid bridges, the only peculi- 
arity which seems to distinguish the inter se 
from the intra se hybrids is the lagging of 
chromosomes, which is quite noticeable in 
five of the former. 

Chromosome Interchange Gives Evidence 
for Position Effect 

This past season a bud sport was found on 
one of our Datura plants which has proved 
of considerable interest. The plant was 
heterozygous for what we have been calling 
a dominant gene, Rough-4 (Rf-4), which 
renders the leaves rough. The gene is ap- 
parently located in the • 1 half-chromosome of 
Prime Type 51, in which this -i fragment 
had been translocated to the 11-12 chromo- 
some by means of the satellite on the • 12 end. 
Dr. Bergner found that in a bud sport which 
differed from the parent plant in having 
smooth leaves and more vigorous growth, a 
segmental interchange had occurred such that 
the • 1 half-chromosome was transferred to 
the 21-22 chromosome. The fact that when 
the • 1 fragment was attached to another 
chromosome the leaves were normal in ap- 



208 



CARNEGIE INSTITUTION OF WASHINGTON 



pearance indicates that the roughness when 
the fragment is attached to the 1 1 • 12 chromo- 
some must be considered due to a position 
effect. This interpretation is confirmed by 
the character of the offspring in the next 
generation. The interchange is also of interest 
since it is the first demonstrated chromosomal 
change of this kind in Datura which has 
taken place spontaneously in somatic tissue. 

Visible Differences between Datura 
Chromosomes 

For some time Miss Satina has been in- 
vestigating the differences in size and struc- 
tural differentiation of the chromosomes in 
Datura stramonium. By study of the chromo- 
somes of prime types and of in-\-\ types in 
pollen grains and root tips, she has found 
that each of the 12 different chromosomes is 
divided by the insertion region into two arms 
of unequal size. The longest primary chromo- 
some (1-2) averages 4.0 microns, the shortest 
(23.24) averages 1.8 microns. The longest 
secondary chromosome (i-i) averages 4.5 
microns, the shortest (19-19) averages 1.8 
microns. Seven of the 12 chromosomes have 
satellites on one of the arms (the 3-4, 7-8, 
9-10, 11 -12, 19.20, 21-22, and 23.24 chro- 
mosomes). Only one of the chromosomes, 
2« + io-io, has as its extra chromosome a 
satellited arm doubled. Each chromosome has 
thus a visible individuality, and Miss Satina 
is now able to distinguish each from all the 
others and to identify the individual ends. 

Genes in Datura 

During the progress of the Datura work 
there have been gradually accumulated new 
tools in the way of methods and plant testers 
which have made possible more effective 
attacks on the problems of heredity and 
evolution. 

An ample collection of genes with which 
to tag the various chromosomes and parts of 
chromosomes is considered an important ele- 
ment in the geneticist's ches